Fundamentals of Electricity & Electronics

CENT-112 Fundamentals of Electricity and Electronics1

CENT-112: Fundamentals of Electricity & Electronics

Dr. Van de Graaff (MIT Professor) designed and built this generator as a research tool in early atom-smashing and high energy X-ray experiments. This is the standard of excellence we should aspire to.


Course Outline• Section 1: Fundamentals of Electricity &

Electronics

• Section 2: Basic Circuits

• Section 3: Motors, Generators, & Power Distribution

• Section 4: Advanced Electrical Circuits

• Section 5: Electronic Communication & Data Systems


Interest• The great end in life is not knowledge but

action. Take your knowledge and use it as soon as you can.

• “Use technology as a blessing to mankind and not as a curse.” Einstein 1879-1955

• Improvement ideas: [email protected]

• Website: http://www.hcc.hawaii.edu/~tomsic

• 12 labs, 2 projects (audio amplifier & PS)

• 3 exams


Introduce Yourself• Where are you from?

• How do you like Honolulu Community College?

• What experience do you have in electronics?

• What is something interesting about yourself?

• What do you want to learn in this class?


Section 1: Fundamentals of Electricity & Electronics

• Safety Precautions

• Basic Electrical Terms and Circuits

• Basic Measuring Instruments

• Basic Electrical Circuit Materials

• Energy

• Sources of Electricity


A GOOD THING TO KEEP IN MIND!


THE BEST TOOLS EVER INVENTED … HANDS!


SAFETY SHIELDS ARE EYE INSURANCE!


SAFETY SHOES ARE NOT FOR DEFEAT!


HEARING PROTECTION IS FOR WINNERS!


Always check Electrical Circuits Deenergized

• Discharge capacitors.

• Check Power Leads (T1-T3)

• Check Capacitors discharged.

• < 30VAC is deenergized.


Electrostatic Discharge (ESD)

• Invisible Threat

• 1 touch can ruin this card.

• Wear a wrist strap.


General Safety Rules1. Do not work when you are tired or taking

medicine that makes you drowsy.

2. Do not work in poor light.

3. Do not work in damp areas or with wet or damp clothing and shoes.

4. Use approved tools, equipment, & protective devices.

5. Remove all metal items when working around exposed circuits.


General Safety Rules Continued6. Never assume that a circuit is off. Double-

check it with an instrument that you are sure is operational.

7. Buddy system is used at circuit breaker supplying power if working on circuit.

8. Never override safety interlocks.

9. Keep all tools and test equipment in good working condition.

10. Discharge capacitors.


General Safety Rules Continued11. Do not remove grounds and do not use adapters

that defeat the equipment ground.

12. Use CO2 or halogenated-type fire extinguisher to put out electrical fires. Water conducts electricity! (i.e. galley fire in oven).

13. Store solvents and other chemicals in appropriate areas. (i.e. fire personnel incident).

14. Do not work on unfamiliar circuits.15. Do not cut corners or rush. No horseplay or

practical jokes in the labs (i.e. throwing caps, meggering).


Shock Victim• Do not become part of the problem.

• Use non-conductive belt and break free shock victim.

• Call for medical assistance. (911)


Review CPR• Check for response.

• Have someone call 911.

• Clear airway.

• Look, listen and feel for breathing.

• Give 2 full breaths.

• 15 compressions (1 and 2 and 3)

• Continue till medical help arrives, you are relieved or are too tired to continue.


Questions

• Q1. Who is responsible for safety?

• A1. Everybody is responsible for their safety.

• Q2. What protects electronic circuits from ESD?

• A2. ESD packaging & wrist straps.

• Q3. What is the worst electrical shock you have heard of or experienced?

• A3. Various.


Scientific NotationPrefix Symbol Decimal Power of Ten

tera T 1,000,000,000,000 1012

giga G 1,000,000,000 109

mega M 1,000,000 106

kilo k 1,000 103

basic unit 1

milli m .001 10 3־

micro μ .000001 10 6־

nano n .000000001 10 9־

pico p .000000000001 10 12־


Ohms Law

E

I R E=IR

Given:

E = Voltage

I = Current

R = Resistance

I = E/R

R = E/I


•Definitions

–Current (I): Flow of electrons past a point. 1A = 1 coulomb of charge flowing past a point for 1 second. Unit of measure is amps.

–Resistance (R): Opposition to the flow of electrons. Unit of measure is ohms.

–Voltage: (E): Force behind electrical flow. Unit of measure is the volt.

Basic Electrical Terms


Questions• Q4. Given a 1 Megohm resistor with a 120 volt

potential applied to it, what current will pass through it?

• A4. .12 milliamps

• Q5. Can this current kill you if you touch it?

• A5. No. .1 Amp for 1 second can be fatal.

• Q6. How many students know CPR?

• A6. It is a good thing to be qualified in CPR when working on or near electrical circuits.


Questions Continued• Q7. Given a 1.5 Amp battery charger with a total circuit

resistance of 8 ohms, what supply voltage is generated?

• A7. 12 volts

• Q8. What amperage is present when you place the new chip in your cellular phone?

• A8. micro amps.

• Q9. What amperage is present when you put leads on a new car battery?

• A9. milliamps


•Atomic Theory

–Foundation for Solid State Devices

–Atom - Smallest part of an element that retains the characteristics of that element.

–Molecule – Smallest part of a compound.

–Compound - 2 or more elements chemically combined.

Definitions


•Atom Parts:–Electrons: Negative part of an atom.

–Protons: Positive part of an atom.

–Neutrons: Negative part of an atom.

The Atom

NPN

P

E

E

EE E

E

EE

EE


Static Electricity• Like charges repel each other and unlike charges

attract each other.

• Walking across a wool or nylon rug , you can generate a static charge of electricity, discharging several thousand volts of electricity to a metallic object like a door handle.


Definitions• Coulomb: Practical unit of measurement of the

amount of electricity. Used to describe the flow of electricity.– 1 Coulomb = 6.24 X 1018 electrons.

• Electrostatic or Dielectric field: The field or force surrounding a charged body.

• Charge Transfer– Direct Contact– Induction: Electron flow due to charged object in

close proximity.


–Valence Electrons are those electrons which are located in the outermost or “Valence” shell of an atom.–The number of valence electrons an atoms has determines the electrical properties of that atom.

< 4 electrons => Conductor

> 4 electrons => Insulator

4 electrons => Semiconductor

Energy Band Diagrams


Energy Band Diagrams Continued

Conductor Semiconductor Insulator

Valence Band Forbidden Band Conduction Band


–Covalent vs. Ionic Bonding–“Octet” Rule and Covalent Bonding

•“N” and “P” Crystals–Base Material - Silicon or Germanium–Doping - Process by which impurity atoms are added into a pure base material to create a compound with improved electrical properties. This process is used when making semiconductors.

Bonding


Static Device Application• Electrostatic Precipitator: Collector Plates need

cleaning.

OilMist

MechanicalFilter

Ionizer Plate:Positively charges

Particles in air

Collector Plate:Negative platescollects + ions.

CleanAir


Basic Electrical Circuit

Power Supply(Source)

Conductor

Load(Light)


Types of Current• AC: Alternating Current

• DC: Direct Current

0

+

-

0

+

-


Circuit Flow• Conventional Current Flow: Hole flow.

• Electron Flow– Series Circuit

– Parallel Circuit– Series/parallel Circuit


Basic Instruments & Measurements

Simpson 260 Fluke 177


Interest• One of the first meter instruments was used

by the Greeks (0 BC) and was the Sun Dial.


Outline• Types of meter movement

• Types of meters– Voltmeter– Ammeter– Ohmmeter

• Electrical diagrams


Basic Multimeters• A meter is a measuring instrument.

• Ammeter: measures current.

• Voltmeter: measures the potential difference (voltage) between two points.

• Ohmmeter measures resistance.

• Multimeter: combines these functions and others into a single instrument.


Ammeter• Measures current in amperes, milliamperes,

microamperes depending on the meter scale.• The coil in the meter movement is wound with

many turns of fine wire.• If a large current was allowed to flow the coil, it

would burn it out, so a shunt or alternate path is provided for current. Most of the current flows through the shunt.

• Safety: Connect an ammeter is series with a circuit device. Never in parallel!


Determining Shunt Resistors• Meter movement requires 1mA for full scale

deflection. The resistance of the coil is 100Ω. The ranges of the meter are: 0-1mA, 0-10mA, 0-50mA, 0-100mA.– E=IR = (.001)(100) = .1V without a shunt. For full

scale deflection, .1V is required.

• A shunt must carry 90% of the current for the 0-10mA scale.– Rs =E/I = .1/.009 = 11.1Ω

• Calculate the other shunt resistors.


Voltmeter• To ensure voltages across the coil never

exceed .1V, multiplier resistors are placed in series with the meter movement coil using a switch.

• Voltage ranges 0-1V, 0-10V, 0-100V, 0-500V• .1V can be placed across meter at any one time,

therefore a resistor must drop .9V to use a 0-1V scale. Full scale current deflection is 1mA or .001A

• Rm = E/I + .9V/.001A = 900Ω• Calculate multiplier resistors for other scales.


Ohmmeter• Uses non-linier scale: zero-infinite.

• Calibrate prior to use for analog meter.

• Check leads at 0Ω for good lead connections.

• Electrical leads safety story for finger stop.


Moving Iron Vane Meter


Moving Iron Vane Meter • Measure either AC or DC.• It depends on induced magnetism for its operation. It

utilizes the principle of repulsion between two concentric iron vanes, one fixed and one movable, placed inside a solenoid. A pointer is attached to the movable vane. When current flows through the coil, the two iron vanes become magnetized with north poles at their upper ends and south poles at their lower ends for one direction of current through the coil. Because like poles repel, the unbalanced component of force, tangent to the movable element, causes it to turn against the force exerted by the springs.


D'ARSONVAL METER MOVEMENT • The permanent-magnet moving-coil movement

used in most meters .


D'ARSONVAL METER MOVEMENT • D'Arsonval meter movement is capable of indicating

current in only one direction.• Without a rectifier, or direct current of the wrong

polarity, the meter would be severely damaged.• Since the pointer will vibrate (oscillate) around the

average value indication, damping is used.1. Airtight chamber containing a vane

2. The movement of the coil (conductor) through a magnetic field causes a current to be induced in the coil opposite to the current that caused the movement of the coil.


Digital Multimeters (DMM)• DMM are smaller and more

accurate in measurement.

• Analog meters can measure transients information better.

• Measures resistance, DC & AC voltage, amperage, and diode testing.


Questions• Q. What is the difference between diode testing

and resistance checking?

• A. The diode check is more sensitive with an audible sound for continuity.

• Q. What are some experiences that you have with different meters?

• A. Various


Electrical Diagrams• One line Diagram

– i.e. Motor Controllers

• Wiring Diagram– i. e. Ceiling Fan

• Block Diagram– i. e. Car Stereo

• Schematic Diagram– i. e. VCR player

L1 L2

M

RF AMP Detector AF AMP

Antenna

Speaker

Not Connected Connected

RC

RB

Q1


Logic Output Amplifier Using a UJT and a SCR

LOAD

INPUT FROM LOGIC

115 VAC

1K10K

+15 VDC LOGIC SUPPLY

Schematic Diagram


Q 1

Q 2

Q 3

Q 4

Q 5

Q 6

Q 7

Q 8

Q 9

Q 10

Q 11

Q 12

C

RU306D S Q

C Q

R

D S Q

M305B

C R

A>B U300

A=B

A0

AB U301

A2

A3

A=B

AB

B2 A=B

B3 AB U302

A=B

A<B

A0

A1

A2

A3 A=B

B0

B1

B2

B3

S300

U304 +12V

Q1

Wiring Diagram


Conclusion


Basic Electrical Circuit Materials


Interest• Optical fiber is a long, cylindrical, transparent material that

confines and transmits light waves.

• Carries information in the form of light giving the fiber thousands of times more information-carrying capacity than copper, which uses electricity to transmit signals.

• 3 LAYERS: – 1. Core: carries the light (silica glass) – 2. Cladding: confines the light to the core (silica glass) – 3. Coating: provides protection for the cladding (plastic)

• Carries information so fast that you could transmit 3 television show episodes in just one second. This is impossible with copper wire.


Basics• Conductor: Pathways that allow electrons to flow

through an electrical circuit.– Electron flow– Hole flow (+ charge flow, opposing viewpoint).– Materials:

• Copper: Most common.• Silver: Better conductor, more expensive• Aluminum: Used in high voltage lines because of its light

weight. Center core is steel for strength.• Brass: Used in electro-mechanical parts like relays and

contactors.


Conductor Sizes• American Wire Gauge System

– The larger the gauge number, the smaller the cross-sectional area the wire will have.

• Circular Mils (cmil)– cmil = Diameter2

– 4 cmil = (2 mil wire diameter) 2

– 1 inch by ¼ inch wire = (1000 mils)(250 mils)/.7854 = 318,309 cmils

0

30

36

15


Conductor Insulation• Insulation: Conductor protective coating.

– Materials: Rubber, plastic and other synthetic materials

– Factors: Extreme heat, cold, chemicals, and oil.– Codings:

• R: Rubber

• H: Heat

• C: Corrosion resistant

– Types: High voltage, Coaxial, multiple conductors, stranded conductors, solid conductors, 3 conductor lighting cord.


Conductor Resistance• Factors that effect resistance.

– Cross-sectional area of the conductor: Larger diameter, lower resistance.

– Type of conductor resistance: Aluminum 1000 feet = 2.57 ohms. Copper 1000 feet = 1.619 ohms.

– Length of conductor: Longer conductor, higher resistance.

– Temperature of material: Higher temperature, higher resistance.


Safety Standards• National Electrical Code (NEC) is a collection of

electrical standards that must be followed to ensure safety of personnel and prevent electrical fires.– Maximum voltage drop for branch circuits (i.e.

breaker panel to outlet) is 3%.– CMA = (K)(I)(L)/VD where CMA = area in cmil, K

= constant (K=12 for copper and 18 for aluminum), I = current, L = length of conductor, VD = voltage drop.


Questions• Q. Given a copper conductor for a 20A drill 75

feet away, what size wire is needed?

• W. Length = (75)(2)=150 VD = (120)(.03)=3.6– CMA = (K)(I)(L)/VD– CMA = (12)(20)(150)/3.6 = 10,000 cmils or No. 10

wire.

• A. No. 10 wire


Breadboards

• Copper strips are run in parallel under the rows of holes and are used as conductor pathways.

• Jumper wires are used to connect all the solid state devices.

• Used to prototype a circuit.


Breadboards


Printed Circuit Board (PCB)



Edge Connectors

Heat Sink

Connection Pad

Conductor Path






Chassis• Chassis: Circuit using metal frame providing

conduction path for the negative side (ground)– i.e. Tail light being supplied by car battery.– i. e. Power supply using chassis resisters.


Switches• Classified by the actuator which is the mechanical

device that causes the circuit to open and close.

• SPST: Single Pole Single Throw – Single Pole: 1 path for electron flow to be turned on &

off.– Single Throw: Switch controls only one circuit.

• DPDT: Double Pole Double Throw– Double Pole: 2 paths for electron flow to be turned on

& off.– Double Throw: Switch controls two circuits.


Toggle Switch


Slide Switch


Rocker Switch


Rotary Switch


Rotary Switch Application


Wafer Switch


Limit Switch


Dip Switch


Questions• Q. What is something that uses a limit switch?

• A. Computer, Camera, Shredder, etc.

• Q. What is something that uses a dip switch?

• A. Back of computer to switch 120 to 240 VAC

• Q. What is something that uses a rocker switch?

• A. Light switch


Switch ratings• Current: Maximum amperage rating to handle

current safely. High current causes high heat.

• Voltage: Maximum voltage rating so that electromechanical circuitry will not fail.


Connectors• Splice lug: Connects 2 wires.

•Wire nut connector: Connect motor with controller.


Wire Cutter Tools


Circuit Protective Devices• Fuses: Open/ blow for circuit protection.

120V5A

•Circuit Breakers: Protect larger rated equipment.-Positions: on, off, trip-free-Explain troubleshooting ACBs.


Incandescent Lamp• In 1879 Thomas

Edison developed the 1st incandescent lamp.

• The tungsten replaced the carbon filament.

• The heat produced from current flow is usually what burns out the filament with time.

Tungsten


Fluorescent Lamp

• When the tube is energized, the filaments at the end will glow producing heat and little light.

• The heat vaporizes the mercury in the tube.• Once the mercury is vaporized, electrons flow in the

mercury vapor. Ultraviolet light is produced.• The light strikes the phosphor coating and causes it to

glow creating phosphorous light. (very little heat)


Lighting Physical Diagram

Starter

Ballast

Light Clip


Fluorescent Lighting Schematic


Neon Light

• 2 Electrodes inserted in the ends of a long glass tube. Tube is filled with neon gas.

• A neon light transformer (≥10,000V) is used to create current through the neon gas. After the light is energized, the neon tube will glow.

• To create a variety of colors, other gasses are added. (i.e. argon and helium)


LED Light


Halogen Lamp• A tungsten filament is

inserted through a glass tube filled with halogen gas.

• Produces more light.• The halogen gas returns

boiled of tungsten particles back to the filament making the filament last longer.

• Creates high heat. Filaments can be damaged from oil on fingers.

light filament


Fiber Lighting from the Sun• Future of lighting


Camera Flash Circuit

NE: Neon Lamp FL: Flash


Resistors• Demonstrate resistor software.


Chip Resistors


Potentiometers• Rotary knob

varies resistance.

• Can use an eraser to clean carbon deposits between arm and resistor.

• Uses: voltage and speed adjust.


Variable Resisters


Wire Wound ResistorsStarting Resistors


Conclusion• Q. When do a use a resistor in a circuit?

• A. provide opposition to current flow or develop a voltage drop.

• Q. What can cause a potentiometer to no longer work?

• A. Loose or broken arm.


Sources of Electricity


Interest• Solar power device use is on the increase.

Devices include cars to radios.


Basic Sources of Electricity• Friction

• Chemical Action

• Light

• Heat

• Pressure

• Magnetism


Battery History• Luigi Galvani (1790): Frog supported on copper

wires leg twitched when touched with a steel scalpel.

• Alessandro Volta: Invented electric/ voltaic cell by placing 2 dissimilar elements in a chemical building an electric potential creating electricity from chemical action.


Battery Experiment• A grapefruit can be used to produce enough

electricity to operate a small radio.

Penny

Nickel


Zinc Carbon Battery Cell• Zn + H2SO4 + H2O ZnSO4 + H2O + H2

- plate + electrolyte + water sulfated - plate + water + hydrogen gas.- End of Life due to H2 blanketing around carbon rod.

H2SO4 + H2O

Zn C

H2

- +


Primary Cells

AAA Cell

AA Cell

C Cell

D Cell


Primary Cells


Primary Cells• Can not be recharged. Chemical action can not be

reversed.

• Defect: Polarization: H2 blanketing around electrode.

• Depolarization agent is added to prevent the H2 blanketing around electrode . Compounds rich in oxygen (i.e. MnO2) are used. The O2 in the depolarization agent combines with H2 to form H2O. (2MnO2 + H2 2MnO3 + H2O):

• Local Action: Does not contribute to electrical energy.


Battery Dry Cell• Flashlight Batteries: Zinc-carbon Cell


AA Alkaline Cell• Anode: Manganese Dioxide• Cathode: Zinc Powder• Electrolyte: Caustic Alkali• Separator: Separates + & -


Mercury Cell• New type of dry cell.

• 1.34 VDC from chemical action between zinc (-) and mercury oxide (+).

• Costly to make

• Creates 5 times more current then other dry cells.

• Maintains terminal voltage longer.

• Uses: field instruments & portable communications.


Lithium Cell• Lithium is bonded to a thin

layer of conductive metal and has a porous separator between it and the cathode.

• This design allows for a large surface area, providing a large reaction surface & higher discharge rates compared to other Lithium cells.


Silver Oxide Cell• Uses amalgamated zinc anode, silver oxide as

the cathode material, & a potassium hydroxide electrolyte.

• Silver oxide cells are ideal for miniature devices where space is limited.

• Voltage: 1.5 to 1.2 V

• Uses: Watches


Silver Oxide Cell


Secondary Cells• Can be recharged or restored.

• Chemical action can be reversed.


Battery Chargers• Used to restore the charge on rechargeable

batteries.

• Used for: AA batteries and car batteries.


Battery Chargers Schematic


Battery Chargers P/S Schematic

• Parts of a Power Supply– Stepdown Transformer

– Bridge Rectifier

– Filters

– Regulator


Battery Charges• Normal: Done when battery is discharged

• Equalizing: Done to drive sulphates off of positive plate.

• Float: Keep at full charge.

• Freshening: New batteries


Incidents• Battery fire due to charging battery.


Battery Wet Cell


Measuring Specific Gravity

Determines state of the charge on the battery.


Lead Acid Battery


Lead Acid Battery• Primary Chemical Reactions

– Pb + PbO2 + 2H2 SO4-2 2PbSO4

-2 + 2H2O + 5 e-

• Half Cell Chemical Reactions– Pb + SO4

-2 = PbSO4-2 + 2 e-

– PbO2 + 4 H+ + 2 e- + SO4-2 = PbSO4

-2

charge

discharge

Pb PbO2

- + H2 SO4-2 H2 O

Electrolyte

Separator


Lead Acid Battery Description• In a wet cell, the metals are sponge lead (Pb) and lead

peroxide (PbO2), and the electrolyte is dilute sulfuric acid (H2SO4).

• The reaction begins as sulfate (SO4) breaks away from the acid and unites with the lead of both the positive and negative plates to form lead sulfate (PbSO4).

• The oxygen (O2) is thereby liberated from the lead peroxide and joins with the hydrogen (H2 -- what's left over after the sulfate left the acid) to produce ordinary water (H2O), which dilutes the electrolyte.


Lead Acid Battery

PlasticCase

TerminalPost

TerminalPost

Separator

Plate

s


Lead Acid Battery• Batteries self- discharge 1-25% per month in

storage

• Lead sulfation starts occurring when the state-of-charge drops below 100%. If left in a vehicle, disconnecting the negative cable will reduce the level of discharge by eliminating the load. Cold will slow the self-discharge process down and heat will speed it up.

• Batteries are recycled by law.


Battery Safety


Nickel-cadmium Cell


Nickel-cadmium Cell• Chemical Reaction:

– 2 NiOOH + 2H2O + Cd 2 Ni(OH)2 + Cd(OH)2

• These batteries contain a Ni(OH)2 cathode, Cd anode and aqueous KOH electrolyte.

• Ni(OH)2 has a layered CdI2 structure, and NiOOH is apparently a complex, multiphase material.

• Advantages: High cycles (often 1000's) and long shelf life (possibly months without significant self-discharge).

• Disadvantages: Relative to Pb acid include lower power densities, greater cost, and a "memory" effect.

charge

dischargeNickel hydroxideOxy-Nickel hydroxide Cadmium hydroxide


Nickel-cadmium Cell• Memory effect: Unused capacity of a cell cannot

be utilized if the cell is not fully discharged. Related to the formation of a passive surface on the electrodes that forms a barrier to further cell reaction.


Nickel-cadmium Cell• Applications:

– Cassette players and recorders

– Dictating machines

– Instruments

– Personal Pagers

– Photoflash equipment

– Portable communications equipment Portable hand tools and appliances

– Shavers

– Tape recorders

– Toothbrushes


Questions• Q. What do you use batteries for?• A. Radios, lights, fans, cars, toys, calculators, cameras,

laptops.• Q. What is the largest battery you have seen?• A. Submarine battery.• Q. What is the difference between rechargeable and

disposable batteries?• A. Rechargeable batteries are made of NiCAD while

disposable batteries are alkaline because NiCAD can be cycled more.


Dirty Cells cause grounds


Cell Damage


Questions• Q. What is the chemical reaction for a lead-acid

battery?

• A. Pb+PbO2+2H2 SO4-2 2PbSO4

-2+2H2O+5 e-.

• Q. What is a button battery made of?

• A. Silver Oxide.

• Q. If your battery is grounded, how do you repair it?

• A. clean it & retest or take it to Sears to check the internal resistance.

charge

discharge


Batteries in Series

1.5V@1A 1.5V@1A 1.5V@1A 1.5V@1A

_ +

Physical Description

Electrical Schematic

++++_ _ _ _Output6 VDC

1A


Batteries in Parallel

_

+

Physical Description


Output1.5 VDC

4A

1.5V@1A

_ _ _

+ + +

1.5V@1A

1.5V@1A

1.5V@1A

+

_


Batteries in Series-ParallelPhysical Description


Output6 VDC

2A

_+

_ _ _+ + +

1.5V@1A

1.5V@1A

1.5V@1A

1.5V@1A

+

_

1.5V@1A

1.5V@1A

1.5V@1A

1.5V@1A

_+

_ _ _+ + +


Battery Capacity• Look at manufacture chart for specifications.

• Capacity in Amp-Hours (AH) is the ability to produce current over a period of time.

• Rate of discharge must be considered in order to get maximum AH out of battery.

• Factors effecting capacity of battery:– Number of plates per cell.– Kind of separators effect capacity & battery life.– General condition of the battery. (i.e. age, grounds,

state of charge).


Other Sources of Electricity• Solar

• Heat

• Crystals

• Fuel Cells

• Diesels

• Generators


Photovoltaic Cell


Photovoltaic Cell• Schematic symbol

+_

• Physical descriptionL

_

+ P type semiconductor

N type semiconductor

Sunlight

• Specifications: 1 cell produces 1 Watt and .5 Volts– Cells can be connected into arrays.– Arrays are build with cells in series and parallel.


Photovoltaic Cell Application• Used to keep solar powered cars charged when

not being driven.


Questions• Q. What are some applications that you have

used a solar cell for?

• A. Cars, calculators, heat new houses.

• Q. What is the current and voltage of 6-6 volt, 2 amp batteries placed in parallel in a spotlight?

• A. 6 Volts and 12 Amps.


Photoresistive Cells• Schematic symbol


PILOT DEVICE

AC OR DC

+VCC

+VOUT

Photoresistive Cell Application•Resistance is proportional to the light source applied.•The circuit below uses a photoresistive call to bias the base of a transistor. The output of this amplifier could be used to power a light (Street Light).


Thermocouple• Schematic symbol

+_

• Physical Description

Copper Wire

Iron Wire

Match

Galvanometer:Measures very Small currents.

Thermocouple

Thermocouple + Galvanometer = Pyrometer

Group of thermocouples = Thermopile


Piezoelectric Effect• Definition: The property of some crystals (i.e.

Quartz) that when a pressure is exerted on one axis, a proportional voltage is present on the other axis.

• Physical Description:

Sound waves QuartzCrystal

pressure electricalwaves

e-

Output


Fuel Cells• Schematic symbol

FC

• Physical descriptionL

Electrolyte

PotassiumHydroxide

KOH

_ +

ElectrodeElectrode

HydrogenGas

OxygenGas

OperationH2 gas supplied develops a –

potential on electrode & ionizes the electrolyte.

O2 gas supplied develops a + potential on electrode & ionizes the electrolyte.

H2O is waste product of chemical reaction with no heat loss.

Used in the space program.

Ratings: 1.23V, 2KW


Magnetohydrodynamic Generator• Magnetohydrodynamic (MHD) electricity is

generated when ionized gas is passed through a magnetic field.

• MHD converter

Coil forMagnetic Field

+_Output

+

_

Anode Plate

Cathode Plate

IonizingGas

(Argon orHelium)

IonizingGas

Gas heated by solar power > 2000F


Generator• Schematic symbols

G

• Output waveform

0

Phase A Phase B Phase C


Generator• Generates 450 VAC, 60 Hz, 3 phase electricity.


Conclusion• Q. Explain a way to produce electricity?

• A. Various

• Q. What is the output waveform of the Hawaiian Electric Company?

• A. 3 Phase Sine Wave.


Series Circuits


Interest• Knowing how to do calculations in series

circuits is one of the basic building blocks in electronics.

• Electronics software products let you download software to run on your computer testing your knowledge of circuit calculations. Demonstrate in class.

• Resistor calculator software.


Series Circuit Formulas• ET = E1 + E2 + E3 … + EN

• RT = R1 + R2 + R3 … + RN

• IT = I1 = I2 = I3 … = IN


Voltage in a Series Circuit• ET = E1 + E2 + E3 … + EN

• Kirchhoff’s voltage law: The source voltage of a series circuit is equal to the total value of each individual voltage drop.

• Example:

ET = 19VER3 = 4VER2 = 8vER1 = 7V

R1 R2 R3


Current in a Series Circuit• IT = I1 = I2 = I3 … = IN

• Total amperes into the circuit is the same across each component that current travels through in a series circuit.

• Example:

IT = 2mAIR3 = 2mAIR2 = 2mAIR1 = 2mA

R3R2R1


Resistance in a Series Circuit• RT = R1 + R2 + R3 … + RN

• Total resistance is equal to the sum of the individual resistances in a series circuit. Total resistance is additive.

• Example:

R3R2R1

R1 = 12Ω R2 = 7Ω R3 = 6Ω

RT = 25Ω


Determining Unknown VoltageER1 = 5V

R1 R2

R3

R4R5

ET = 24VDC

ER2 = 7V

ER4 = 2VER5 = 1V ER3 = ?V

Q. What is the voltage drop across R3?

W. 24-(5+7+1+2)=

A. 9 VDC


Determining PowerER1 = 2V

R1 R2

R3

R4R5

IT = 3A

ER2 = 3V

ER4 = 5VER5 = 6V ER3 = 4V

Q. What is the total power in the circuit?

W. (2V)(3A) + (3V)(3A) + (4V)(3A) + (5V)(3A) + (6V)(3A) = 6W + 9W + 12W + 15W + 18W =

A. 60 Watts

Given: Power = EI


QuestionsER1 = 1V

R1 R2

R3

R4R5

IT = 5A

ER2 = 2V

ER4 = 9VER5 = 2V ER3 = 3V


W. (1V)(5A) + (2V)(5A) + (3V)(5A) + (9V)(5A) + (2V)(5A) = 5W + 10W + 15W + 45W + 10W =

A. 85 Watts


Questions ContinuedER1 = 1V

R1 R2

R3

R4R5

ET = ?VDC

ER2 = 3V

ER4 = 2VER5 = 1V ER3 = 5V

Q. What is the voltage of the power supply?

W. 1+3+5+2+1=

A. 12 VDC


Questions ContinuedER1 = ?V

R1 R2

R3

R4R5

ET = 2, 555VDC

ER2 = 1KV

ER4 = .001MVER5 = 500V ER3 = 45V

Q. What is the voltage of R1?

W. 2,555-(1000+45+1000+500)=

A. 10 VDC


Using Ohms Law in Series Circuits

R1 R2

R3

R4R5

ER2 = 12V

Q. What is the total current in the circuit?

W. 12/4=

A. 3A

R2 = 4Ω

Given: E = IR


Troubleshooting a Lighting Circuit

R1

L1

T1

IsolationTransformer

Half WaveRectifier

D1

D2

24VAC

IL1=4A

Q. RI has an open (is damaged), what will be the ratingOf the new resistor?

W. 24/4=

A. 6Ω


Using a Voltmeter

R1 R2

R3R4

F1 SW16VDC Open

Voltmeter 1= 6 VDC

Voltmeter 2= 0 VDC

+

+ +_

__

10Ω 10Ω

10Ω10Ω


Using a Voltmeter Continued

R1 R2

R3R4

F1 SW16VDC Shut

Voltmeter 1= 0 VDC

Voltmeter 2= 1.5 VDC

+

+ +_

__

10Ω 10Ω

10Ω10Ω


R1 Shorted

R1 R2

R3R4

F1 SW16VDC Shut

Voltmeter 1= 0 VDC

Voltmeter 2= 2 VDC

+

++_

__

10Ω 10Ω

10Ω10Ω


R1 Open

R1 R2

R3R4

F1 SW16VDC Shut

Voltmeter 1= 6 VDC

Voltmeter 2= 0 VDC

+

++_

__

10Ω 10Ω

10Ω10Ω


Questions

R1 R2

R3R4

F1 SW16VDC Shut

Voltmeter 1 Voltmeter 2

+

+ +_

__

10Ω 10Ω

10Ω10Ω

Q. Fuse 1 has blown, what will be the voltage across it?A. 6 VDCQ. Fuse 1 has blown, what will be the voltage across R1?A. 0 VDC


Conclusion• Q. How is E, I, R calculated in series circuits?

• A. 1. ET = E1 + E2 + E3 … + EN 2. RT = R1 + R2 + R3 … + RN

3. IT = I1 = I2 = I3 … = IN

• Q. What voltage is read across a shorted resister in a series circuit?

• A. 0 V


Parallel Circuits


Interest• The resistors in chips

2X scale 10X scale


Parallel Circuit Formulas• IT = I1 + I2 + I3 … + IN

• ET = E1 = E2 = E3 … = EN

• RT = 1/(1/R1 + 1/R2 + 1/R3 … + 1/RN)

• RT =R1R2/(R1 + R2)


Parallel Circuit Voltage

ER1 = 24V

R1 R2 R3 R4ET = 24VDC

ER2 = ?V ER4 = 24V

Q. What is the voltage drop across R2?

W. ET = ER2

A. 24 V

ER3 = 24V

•ET = E1 = E2 = E3 … = EN


Kirchhoff’s Current Law• The algebraic sum of all currents entering any

point will equal the sum of all currents leaving that point.

• Simply stated: The current flowing into a junction of parallel resistance is equal to the current flowing out of the same junction.

• Branch current: Individual currents.

• Mainline current: Total current.


Parallel Circuit Current

IR1 = 5A

R1 R2 R3 R4

IT = 16A

IR2 = ?A IR4 = 1A

Q. What is the current passing through R2?

W. IR2 = IT – (IR1 + IR3 + IR4) = 16 – (5 + 8 + 1)

A. 2A

IR3 = 8A

•IT = I1 + I2 + I3 … + IN

IT = 16A


Parallel Circuit Resistance

RR1 = 34Ω

R1 R2 R3 R4RT = ?Ω

RR2 = 17Ω RR4 = 4.25Ω

Q. What is the total resistance in the circuit?

W. RRT = 1/(1/RR1 + 1/RR2 + 1/RR3 + 1/RR4 )

= 1/(1/34 + 1/17 + 1/8.5 + 1/4.25) = 1/(1/34 + 2/34 + 4/34 + 8/34) = 1/(15/34) = 34/15A. RT = 2.27Ω

RR3 = 8.5Ω

•RT = 1/(1/R1 + 1/R2 + 1/R3 … + 1/RN)



RR1 = 34Ω

R1 R2RT = ?Ω

RR2 = 17Ω


W. RT = R1R2/(R1 + R2) = (34)(17)/(34 +17) = 578/51A. RT = 11.33 Ω

•RT =R1R2/(R1 + R2)



RR1 = 7.5KΩ

R1 R2RT = ?Ω

RR2 = 250Ω


W. RT = R1R2/(R1 + R2) = (7500)(250)/(7500 + 250) = 1,875,000/7750A. RT = 241.94 Ω

•RT =R1R2/(R1 + R2)



RR1 = 3.4KΩ

R1 R2 R3 R4RT = ?Ω RR2 = 2.1KΩ RR4 = 2.1KΩ


W. RRT = 1/(1/RR1 + 1/RR2 + 1/RR3 + 1/RR4 )

= 1/(1/3.4 + 1/2.1 + 1/1.6 + 1/2.1) = 1/(.294 + .476 + .625 + .476) = 1/(1.871)A. RT = .534KΩ

RR3 = 1.6KΩ

•RT = 1/(1/R1 + 1/R2 + 1/R3 … + 1/RN)


Parallel Circuit Equal Resistance

RR1 = 8KΩ

R1 R2 R3 R4RT = ?Ω RR2 = 8KΩ RR4 = 8KΩ


W. RRT = R/N

= 8KΩ/4A. RT = 2KΩ

RR3 = 8KΩ

•RT = R/N


Parallel Circuit Troubleshooting

R1 R2 R3 R4ET = 24VAC

Q. What must be checked before working on a circuit?

A. No voltage in circuit.

Voltmeter= 0 VAC

L2

L1T1

T2

FusesRemoved


Questions• Q. What law can be used to do calculations in

parallel circuits

• A. Ohms Law

• Q. Given a total resistance of 12KΩ, what would be the equal parallel resistance for 4 resistors in parallel?

• W. R = RRT/N = 12KΩ/4

• A. 4KΩ



R1 R2 R3 R4

Q. What caused the fuses to blow?

A. R1 shorted.

Ohmmeter= 0Ω

L2

L1T1

T2

FusesBlown ET = 24VAC

RR2 = 250ΩRR1 = 250Ω RR3 = 250Ω

RR4 = 250Ω




Q. What fault is present in this circuit and why?

A. R4 is open. Rt should be 3Ω for 4 parallel equal resistors. R4 is visually open.

L2

L1T1

T2

FusesRemoved

RR1 = 12Ω RR2 = 12Ω RR3 = 12Ω

RR4 = 12Ω

Ohmmeter= 4Ω




L2

L1T1

T2

RR1 = 4Ω RR2 = 2Ω RR3 = 2Ω

RR4 = 4Ω

Ammeter= ?A

A. 667mA?

Q. What is total circuit current indicated on the ammeter?


Conclusion• Q. How must an ammeter always be connected

in a circuit?

• A. In series

• Q. What is a fault condition that can cause fuses to blow or circuit breakers to trip open?

• A. Shorted circuit component.


Series-Parallel (Combination) Circuits


Interest• Camera resistors: small and precise.


Reducing a Complex Circuit• Total Resistance: Equivalent resistance in a

circuit.

• Series-Parallel Circuit: Combination circuit.

• Reduce combination circuit to a simple series circuit.


Reducing to a Simple Series Circuit

RR1 = 6KΩR1

R2RT = ?Ω RR2 = 400Ω

Q. What is the total resistance in the circuit?W. RR1-R2 = R1R2/(R1 + R2) = (6)(.4)/(6 + .4) = 2.4/6.4 RR1-R2 = .375 KΩ RR1-R2-R3 = RR1-R2 + R3

= .375 + 1.6A. RT = 1.975K Ω

R3

RR3 = 1.6KΩ

Step 1



Q. What is the total resistance in the circuit?W. RR1-R2 = R1 + R2 = 4 + 20 = 24 Ω RR1-R2-R3 = RR1-R2R3/(RR1-R2 + R3) = (24)(12)/(24 + 12) = 288/36 = 8 Ω RR1-R2-R3-R4 = RR1-R2-R3 + R4 = 8 + 12

A. RT = 20 Ω

RR1=4ΩR1 R2

RT = ?Ω

RR2=20Ω

R3RR3 = 12Ω

Step 1

RR4 = 12ΩR4

Step 2



Q. What is the total resistance in the circuit?W. RR1-R2 = R1 + R2 = 3 + 6 = 9 Ω RR1-R2-R3 = RR1-R2R3/(RR1-R2 + R3) = (9)(9)/(9 + 9) = 81/18 = 4.5 Ω RR5-R6 = R5 + R6 = 18 + 9 = 27 Ω RR4-R5-R6 = RR5-R6R4/(RR5-R6 + R4) = (27)(12)/(27 + 12) = 324/39 = 8.308 Ω RR1-6 = RR1-R2-R3 + RR4-R5-R6 = 4.5 Ω + 8.308 Ω

A. RT = 12.808 Ω

RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC


Using Ohms Law• Formulas for the last circuit:

– Determine overall values.

– ET/RT=IT

– Determine individual values using series & parallel rules.

– ER1-R2-R3=ITRR1-R2-R3

– ER1-R2-R3=ER3

– ER3/RR3=IR3

– IT-IR3=IR1-R2

– IR1=IR2=IR1-R2

– ER1=IR1RR1

– ER2=IR2RR2


Ohms Law Combination Circuit 1

Q. What is the total current in the circuit?W. IT=ET/RT=10/ 12.808

RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC

A. IT=.7808AQ. What is the current passing through R4?W. ER4-R5-R6=ITRR4-R5-R6=(. 7808)(8.308)=6.487V ER4-R5-R6=ER4=6.487V IR4=ER4/RR4=6.487/12A. IR4=.5406A


RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC

Q. What is the current passing through R5?W. IR5=IT-IR4= (.7808)-(.5406)

A. IR5 =.2402AQ. What is the current passing through R6?W. IR6=IR5

A. IR6= . 2402A




RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC

Q. What is the voltage passing through R5?W. ER5=IR5RR5= (.2402)(18)

A. ER5 =4.3236VQ. What is the voltage passing through R6?W. ER6=IR6RR6= (.2402)(9) or ER6=ER5-R6-ER5=6.487- 4.324

A. ER6 =2.1618V



Q. What is the ammeter reading in the circuit?W. IT=ET/RT=10/12.808

RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC

Q. What is the current passing through R3?W. ER1-R2-R3=ITRR1-R2-R3=(.7808)(4.5)=3.5136V ER1-R2-R3=ER3=3.5136V or Et-ER4-R5-R6=10-6.487=3.513V IR3=ER3/RR3=3.5136/9A. IR3=.3904A

A

A. IT=.7808A



RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC


A. IR1=.3904A

A

W. IR1=IT-IR3= (.7808) - (.3904)

Q. What is the current passing through R2?W. IR1=IR2

A. IR2= .3904A



RR1=3ΩR1 R2

RT = ?Ω

RR2=6Ω

R3RR3 = 9Ω

Step 1

RR4 = 12ΩR4

Step 2 R5

R6

RR5 = 18Ω

RR6 = 9Ω

Step 3

Step 4ET = 10VDC

A

Q. What is the voltage passing through R1?W. ER1=IR1RR1= (.3904)(3)

A. ER1 =1.1712VQ. What is the voltage passing through R2?W. ER2=IR2RR2= (.3904)(6) or ER2=ER1-R2-ER2=3.513-1.171

A. ER2 =2.342V


Sample Problem 1


RR1=6ΩR1

R2RT = ?ΩRR2=2Ω

R3RR3 = 6Ω

RR4 = 4ΩR4

R5RR5 = 8Ω

ET = 12VDC

A

W. RR4-R5 = R4 + R5 = 4 + 8 = 12Ω RR3-R4-R5 = RR4-R5R3/(RR4-R5+R3)=(12)(6)/(12+6) = 72/18 = 4Ω RR2-R3-R4-R5 = RR3-R4-R5+RR2=4+2=6Ω RR1-5=RR2-R3-R4-R5RR1/(RR2-R3-R4-R5+RR1)=(6)(6)/(6+6) = 36/12A. RT= 3Ω


Sample Problem 1 Continued 1

Q. What does the ammeter read in the circuit?

RR1=6ΩR1

R2RT = ?ΩRR2=2Ω

R3RR3 = 6Ω

RR4 = 4ΩR4

R5RR5 = 8Ω

ET = 12VDC

A

W. IT=ET/RT=12/3

A. IT=4A

Q. What is the current passing through R1?W. ET=ER1=12V IR1=ER1/RR1=12/6A. IR1=2A


Sample Problem 1 Continued II

RR1=6ΩR1

R2RT = ?ΩRR2=2Ω

R3RR3 = 6Ω

RR4 = 4ΩR4

R5RR5 = 8Ω

ET = 12VDC

A

Q. What is the current passing through R2?W. ET=ER2-R3=12V IR2=IR2-R3=ER2-R3/RR2+(R3,R4,R5)=12/(2+4)

A. IR2=2AQ. What is the voltage drop across R2?W. ER2=IR2RR2= (2)(2)A. ER2=4VQ. What is the voltage drop across R3?W. ER3=ET- ER2 = 12-4A. ER3=8V


Sample Problem 1 Continued III

RR1=6ΩR1

R2RT = ?ΩRR2=2Ω

R3RR3 = 6Ω

RR4 = 4ΩR4

R5RR5 = 8Ω

ET = 12VDC

A

Q. What is the current passing through R4?W. ER3=ER4-R5=8V IR3=ER3/RR3=8/6=1.3A IR4=IR2- IR3=2 - (1.333) Kirchhoffs Current LawA. IR4=.6667AQ. What is the voltage drop across R4?W. ER4=IR4RR4= (. 6667)(4)A. ER4=2.667VQ. What is the voltage drop across R5?W. ER5=IR5RR5= (. 6667)(8)A. ER5=5.333V


Sample Problem 1 Continued IV

RR1=6ΩR1

R2RT = ?ΩRR2=2Ω

R3RR3 = 6Ω

RR4 = 4ΩR4

R5RR5 = 8Ω

ET = 12VDC

A

Q. Explain Kirchhoffs Current Law.W. IT=Ipoint1 + Ipoint2 + Ipoint3=2 + (1.333) + (.666) = 4AA. Total current in circuit = current out of circuit.Q. Why isn’t the voltage drop across R3 = 12VDC?W. ER2=IR2RR2= (2)(2) = 4VDCA. 4 VDC is subtracted because of the nature of

voltage in a series circuit within a combination circuit.

Point 1 Point 2 Point 3


Questions

RR1=3ΩR1

R2RT = ?ΩRR2=9Ω

R3RR3 = 9Ω

RR4 = 6ΩR4

R5RR5 = 3Ω

ET = 9VDC

A


A. IR2=.6667A

R6RR6 = 18Ω

R7RR7 = 9Ω

W. RR6-R7=RR6 + RR7=18+9=27ΩRR5-R6-R7 =RR6-R7R5/(RR6-R7+R5)=(27)(3)/(27+3)=81/30= 2.7Ω RR4-7=RR5-7 + RR4=2.7+6=8.7Ω RR3-7 = RR4-7R3/(RR4-7+R3)=(8.7)(9)/(8.7+9)=78.3/16.7=4.689Ω RR2-7=RR3-7 + RR2= 4.689 +9=13.689Ω RT = RR2-7RR1/(RR2-7+RR1)=(13.689)(3)/(13.689+3)= 41.066/16.689 =2.461Ω IT=ET/RT=9/2.461= 3.657A IR1=ER1/RR1=9/3=3A IR2=IT- IR1= 3.657- 3


Power• Power = Work/Time = (Force)(Distance)/Time

• P=EI given: Power (watts), E (volts), I (current)

• Watt: 1 volt of electrical pressure moves 1 coulomb of electrons past a given point in a circuit in 1 second.

PI E


Ohm’s Law and Watts Law

P IER

EII2R

IRPR

P/R

P/EE/R

E2/R

E2/PE/I

P/I2 P/I


Questions

RR1=3ΩR1

R2RT = ?ΩRR2=9Ω

R3RR3 = 9Ω

RR4 = 6ΩR4

R5RR5 = 3Ω

ET = 9VDC

A


A. PT = 32.913 W

R6RR6 = 18Ω

R7RR7 = 9Ω

W. PT = IT2RT = (3.657A)2(2.461 Ω) = (13.274)(2.461)

Q. What is the minimum power rating for R1?W. PR1 = ER1RR1 = (9V)(3 Ω)

A. PR1 = 27 Watts


Troubleshooting• Eliminate parallel paths when checking electrical

components.


Conclusion

RR1=2.4KΩR1

R2RR2=3.6KΩ

R3RR3 = 1.2KΩ

ET = 120VAC

A

Q. What is the total power in the circuit in KW?

A. PT = 192KW

W. W. RR2+R3= RR2 + RR3 = (3600Ω)+(1200 Ω)= 4800ΩRT=RR2+R3RR1/ RR2+R3+RR1 =(4800)(2400)/4800+2400= 11520000/7200=1600Ω PT = ETRT = (120V)(1600 Ω)

G


Series Tuned Circuits1 . Theory

a . Ideal Series resonant circuit contains no resistance. It contains only inductance and capacitance that are in series with each other and with the source voltage.

2 . Operationa . At Resonance ( XL = XC ); therefore, XL + XC = 0. The

resultant reactance is equal to 0. Impedance ( Z ) is minimum.

b . Since Z is minimum, current is maximum for a given voltage. Maximum current flow causes maximum voltage drops across individual reactances.

Tuned Circuits


QuestionsQ. What is the formula for XL?

A. XL = 2 II f L.

Q. What is the formula for XC?

A. XC = 1 / 2 II f C.

Q. What is the resonant frequency in a typical tuned circuit?

A. XL = XC, Fr = .159/Square root LC.


2 . Operation (Continued)c . When Frequency is < Resonance:

- XC => current is lower => voltage drops across reactances are lower.

d . When Frequency is > Resonance:

- XL => current is lower => voltage drops across reactances are lower.

Tuned Circuit Operation


e . Series Tuned Circuit (Schematic)

C1L1

R1

GEN



f . Series Tuned Circuit Analysis XL

XC

oR = Z 0o

XC - XL

XC

XL

o

BELOW RESONANCE

CU

RR

EN

T

IMP

ED

AN

CE

RESONANCE

Z = R

ABOVE RESONANCE

XL

XL - XC

XC

o

100 200 300 500 600 700Fr



1. Theory

a . Called a “tank” circuit because it can store energy.

b . It has the ability to take the energy fed to it from a power source and store this energy alternately in the inductor and capacitor.

c . The resulting output is a continuous ac sine wave.

2 . Operation

a . Voltage is the same across the inductor and capacitor. (parallel)

b . Current through the components varies inversely with their reactances.

c . Total current through the circuit is the vectoral sum of the two individual component currents.

d . IL and IC are 180o out of phase.

e . At resonance, IL and IC cancel each other out => no current from source.

Parallel Tuned Circuits


3 . Application a . At resonance, the circuit has a maximum impedance

which results in minimum current drawn from the source.


4. Schematic Circuit

C1

L1

R1

GEN



5 . Circuit analysis

IC - IL

IC

IL

o

BELOW RESONANCE

CU

RR

EN

T

IMP

ED

AN

CE

RESONANCE

ABOVE RESONANCE

IL

IL - IC

IC

o

100 200 300 500 600 700Fr

IL

IC

o

I

Z



6 . Applications

a . Tuned Amplifier

L1

RL

+

0

VIN

+VCC

RB

C1

CC

0

IMAX

T



QuestionsQ. What are some examples of a parallel tuned

amplifiers?

A. Antenna tuners, air signal tracker, ham radio, transponders (ID aircraft etc).

Q. What crystal can replace the RLC circuit to make it last longer?

A. Piezoelectric Crystal.


b . Pulsed Amplifier: 3 main sections

1. Gain Amp 2. Input Gate Signal 3. Tank Circuit

L1

+

0

VIN

+VCC

R1

C2

C1

OUTPUT SIGNAL

Pulsed Amplifier


INPUT GATE

T0 T1 T2 T3

OUTPUT SIGNAL

Pulsed Amplifier


c. Tuned Amplifier: 3 main sections

1. Gain Amp 2. Positive Feedback Circuit 3. Frequency Determining Device

L1

+

0

VIN

+VCC

R1

Cy1

C1

OUTPUT SIGNAL

Tuned Amplifier


SATURATION

SATURATION

CUTOFF

CUTOFF

OUTPUTINPUT

C1 C2

R2R1

Q1

+VCC-VEE

Overdriven Amplifier


a . The input signal drives the transistor into and out of saturation and cutoff.

b . When the transistor is in saturation and / or cutoff, that portion of the input waveform is “clipped” and the output is distorted.

Overdriven Amplifier


Magnetism and Relays


Interest• The magnetic field of the sun


Experiments Using MagnetsRing magnetsHorseshoe magnet

Bar magnets

Ferris magnets

Coils


Phobos Large Magnet


Basic Magnetic Principles• Magnetic Poles

– South Pole– North Pole– Magnetic lines of force exist between the north and

south poles. Like poles repel. Opposite poles attract.– Each magnetic line of force is an independent line.

None of the lines cross or touch a bordering line.

• Natural Magnets: Lodestones were used by mariners for navigation.

• The Earth is a large magnet surrounded by a magnetic field. (i.e. degaussing coils).


Questions• Q. What are some uses for magnets?

• A. Relays, Levetron, hold things in place.

• Q. How can a magnet loose its magnetism?

• A. Pounding or dropping magnets upsets the molecular alignment and weakens the magnet. Heat sources also destroy magnets by causing increased molecular activity, expansion and a return to the molecules random positions.


Magnetic Flux• Magnetic flux: The many invisible lines of

magnetic force surrounding a magnet.

• B=Φ/A – B=Flux density in gauss (webers per square

centimeter)– Φ(phi)=Number of lines– A=Cross sectional area in square centimeters

• 3rd Law of Magnetism: – The attractive force increases as the distance of the

distance between the magnets decrease.– Magnetic force varies inversely with (Distance)2


LHR for CoilsThumb: Points in directionOf fluxFingers: Wrap around coilIn direction of current


Magnetism in a Coil

Q. What is the direction of flux in this coil?

W. Use LHR for coils.

A. Thumb points right.


LHR for Conductors

Thumb: Points in directionof current.

Fingers: Wrap around coilIn direction of circular magneticField.


Magnetism Tools• Magneprobe


Magnetism Computer Programs

Used forcomponentdesign.


Reluctance• Φ=F/R

– Φ= Total number of lines of magnetic force in gilberts.

– F= Force producing the field.– R= Resistance to the magnetic field. (Reluctance)


Electromagnets• Parts of Electromagnets

– Iron Core– Coil

• Residual Magnetism:– Retentivity of the iron

core.


Electromagnet Diagram• Q. What type of diagram is

this?

• A. Wiring Diagram.


Magnetic Relay


Magnetic Relay Continued• Relay: Device used to control a large flow of

current by means of a low voltage, low current circuit. A relay is a magnetic switch.– Coil: Attracts armature because of magnetism.– Armature: Lever Arm.– Contacts: Normally open (NO) Normally closed (NC)

• Relay Maintenance:– Burnishing tool cleans contacts– Silver plated armatures should be replaced if there is

exposed copper.


Magnetic Relay Physical Description


Timing Relay• Timing Relays energize contacts for a specific

amount of time based on the adjustable setting.

• Contacts are timed on and off.


Relay Controller Schematic

20A

120 VAC, 60 HZ, 1Φ

Stop Button

Start Button Reset Button

M

20A

AM1 TR2

M2TR

CB

DA AC

M2M1~

ED

BE ETR1


Magnetic Circuit Breaker• Parts

– Operating Mechanism

– Tripper Bar– Arc Chutes– Frame– Rack out

mechanism– Indication


Manual Breakers• Manual breakers are shut locally at the

switchboard.

• Magnetic circuit breakers are shut remotely from a control station.


Doorbell


Buzzer Circuit


Magnetic Shields• Shielding is done using the permeability of some

other substance.

• Magnetic lines of force flow through the path of least resistance.

N S

Shield


Magnetic Levitation Transportation


Magnetic Levitation Transportation• HSST is a magnetic levitation transportation

system that has been developed in Japan by HSST Development Corporation established in 1993.

• The HSST is magnetically-levitated (not supported by wheels) and is propelled by a linear induction motor (LIM), not by conventional rotary electric motors.


Conclusion• Q. How does a relay work?• A. Coil energizes, armature engages, secondary

contact shuts/opens.• Q. When would a use a magnetic circuit breaker?• A. Used in electric plants to parallel generators

and switchboards.• Q. What is the LHR for conductors?• A. Fingers: wrap around coil. Thumb: points in

direction of current.


Impurity Atoms:•Trivalent: Boron (B), Aluminum (Al), Gallium (Ga), Indium (ln). Has three (3) valence electrons.

–Known as an “Acceptor Impurity.”•Pentavalent: Phosphorous (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi). Has five (5) valence electrons.

–Known as a “Donor Impurity.”

Diodes


–“N - Type” Material:•Pure base material doped with a Donor Impurity.•Majority Current Carrier: Electrons•Minority Current Carrier: Holes

–“P - Type” Material:•Pure base material doped with an Acceptor Impurity.•Majority Current Carrier: Holes•Minority Current Carrier: Electrons

PN Material


–Old Method: Grown Crystals.

–Newer Methods:

•Alloy Fused: N & P material made using heat / pressure.

•Diffused: N & P gas and heat.

–Both methods are used to produce a “PN” Junction.

Construction


Questions

Q) What is meant by a donor impurity?

A) 5 valiant electrons in outer shell.

Q) What are 4 examples of a donor impurity?

A) Phosphorous, Arsenic, Antimony and Bismuth.


• Potential Hill (Junction Barrier) : Electrostatic field set up across a PN junction which prevents further combination of majority current carriers.

• The value of the voltage of the potential hill depends on the type of base material used during diode construction.

1. Silicon (.5 - .8V)

2. Germanium (.2V)• Rated for up to 1500A / 3000V.• Used primarily in Rectifiers.

Diode Definitions


Operations & Definitions

•Forward Bias: External voltage applied which opposes the potential hill, effectively reducing the width and resistance of the depletion region. => Majority Current Carriers flow through the PN junction.

•Reverse Bias: External voltage applied which aids the potential hill, effectively increasing the width and resistance of the depletion region. => No Majority Current Carriers flow through the PN junction.


Rectifier Diode Block Diagram

+ + +

+ P +

+ + +

Anode Cathode

Potential Hill (Junction Barrier)

Depletion Region

- - -

- N -

- - -

- -

- -

- -

- -

+ +

+ +

+ +

+ +


Rectifier Diode Schematic Diagram

Anode Cathode


Diode Forward Bias

+ + +

+ P +

+ + +

Anode Cathode


Depletion Region

- - -

- N -

- - -

-

-

-

-

+

+

+

+ + -


Diode Reverse Bias

+ + +

+ P +

+ + +

Anode Cathode


Depletion Region

- - -

- N -

- - -

- - -

- - -

- - -

- - -

+ + +

+ + +

+ + +

+ + + +-


Characteristic Curve

+I (mA)

Forward Bias

Reverse Bias

-I (uA)Avalanche Breakdown

+V a -c-V a -c


Zener Diode

–The Zener diode is a heavily doped diode which, as a result of doping, has a very narrow depletion region. This allows the diode to be operated in the reverse biased region of the characteristic curve without damaging the PN junction.

–“Zener Effect”: The area of Zener diode operation (<5V) where the Diode maintains a constant voltage output while operating reverse biased.

–“Avalanche Effect”: >5V applied to the diode while reverse biased which tends to cause the diode to eventually breakdown due to heat generation within the lattice structure of the crystal.


Zener Diode Schematic Symbol

Anode Cathode


Characteristic Curve

Operating Region

Reverse Bias

Forward Bias

+ V a - c- V a - c

I (mA)

I (uA)


Zener Operation

•Ratings: .25V to 1500V

•Used in SSMG / SSTG AC voltage regulator for the reference circuit.

When a higher constant voltage is desired, the zener diodes will be “Stacked” together in series and their voltages will add together to make the higher desired voltage.

This is the case in the SSMG / SSTG AC voltage regulators where four (4) 6v zener diodes are stacked to provide a 24V reference to the comparison circuit.


Zener Diode Voltage Regulator

R1

CR1

Vin Vout


Signal Diode

•Same construction as the Rectifier Diode except that it is designed to operate with a very short “reverse recovery time” to allow it to rectify high frequency AC inputs.


Power Supplies

•Components and their function–Transformer - Receives the AC input from the distribution system and either steps up or down the voltage.–Rectifier - Converts the AC input voltage from the transformer to a pulsating DC voltage.–Filter - Smoothes out the DC pulsations or ripple received from the rectifier.–Regulator - Receives a smoothed DC voltage from the Filter Stage and produces a steady DC voltage to be used by electronic circuitry.


Half - Wave Rectifier

VOUTVIN

1 : 1

T1

CR1

R1


• Positive half-cycle the diode is Forward Bias (FB), negative half-cycle the diode is Reverse Bias (RB).

Half - Wave Rectifier Operation

VDC = VPK X .318Where: VDC = Average DC voltage

VPK = Peak input voltage

.318 = Constant


Full - Wave Rectifier

VOUTVIN

1 : 1

T1

CR1

R1

CR2


• Positive half-cycle, 1 diode is FB, negative half-cycle the other diode is FB.

Full - Wave Rectifier Operation



.637 = Constant


Full – Wave Bridge Rectifier

VOUTVIN

1 : 1

T1

CR1

R1

CR2

CR3CR4


• Positive half-cycle, 1 diode is FB, negative half-cycle the other diode is FB.

Full - Wave Bridge Rectifier Operation



.637 = Constant


Filters

•A filter uses the characteristics of Inductors and Capacitors to smooth the pulsating DC waveform supplied by the Rectifier.

–Types•High Pass - A series RC filter whose output is taken from the resistor.

•Series / Parallel - A filter configuration which uses combinations of capacitors and inductors to smooth the voltage and current pulsations from the rectifier output.


• Rapid charge time constant for filter capacitors and inductors.

• Slow discharge time constant for filter capacitors and inductors.

Ideal filter characteristics


Capacitor Filter Configuration

RB

C1

VIN VOUT

•Capacitor Input Filter Schematic Diagram


Capacitor Filter Operation

•Charge RC time constant is developed from the internal resistance of the rectifier diodes and the capacitance of the filter capacitor. The net result is that the low resistance of the rectifier diodes develop a rapid charge RC time constant.

•Discharge RC time constant is developed from the filter capacitor and the load resistance. Since the load resistance is rather large, the discharge RC time constant is somewhat long.

•RB is called the “Bleeder Resistor” because it provides a path for the filter capacitor(s) to discharge when power is removed from the circuit. RB has a very large resistance and usually draws <10% of normal operating current.


LC Choke Filter Configuration

•LC Choke Filter Schematic Diagram

RB

C1

VIN VOUT

L1


LC Choke Filter Operation

•Charge RC time constant is developed from the internal resistance of the rectifier diodes, the Low DC resistance of the inductor (L1), and the capacitance of the filter capacitor. The net result is that the low resistance of the rectifier diodes and inductor (L1) develop a rapid charge RC time constant.

•Discharge RC time constant is developed from the filter capacitor and the load resistance. Since the load resistance is rather large, the discharge RC time constant is somewhat long.

•The Inductor acts to smooth out the current pulsations produced by the rectifier and / or transformer stage of the power supply.


RC PI Filter Configuration

•RC PI Filter Schematic Diagram

RB

C2

VIN VOUTC1

R1

VOUT(C1)

VOUT (C2)

Charge Path

Discharge Path


RC PI Filter Operation

•First Capacitor provides most of the filtering action.•Second Capacitor Provides additional voltage filtering.•Resistor limits current flow to the desired value and establishes the RC time constants for both filter capacitors.


LC PI Filter Configuration

•LC PI Filter Schematic Diagram

RB

C2

VINC1

L1

VOUT(C1)

VOUT (C2)

Charge Path

Discharge Path


LC PI Filter Operation

•First Capacitor provides most of the filtering action.•Second Capacitor Provides additional voltage filtering.

•Inductor opposes changes in current flow to reduce current spikes and establishes the RC time constants for both filter capacitors.


Voltage Regulators

R1

CR1

Vin Vout

–Series Regulator•Acts as a variable resistor in series with the load.

–Zener Diode Voltage Regulator•Schematic


Voltage Regulator Operation

R1CR1

Vin Vout

VIN

VOUT


Transistor Voltage Regulators

Vin Vout


OPAMP Voltage Regulators

Vin Vout

-+


Tubes, Transistors and Amplifiers


InterestIn 1947, Bardeen & Brattain at Bell Laboratories created the first amplifier! Shockley (boss), came near to canceling the project. The three shared a Nobel Prize. Bardeen and Brattain continued in research (and Bardeen later won another Nobel). Shockley quit to start a semiconductor company in Palo Alto. It folded, but its staff went on to invent the integrated circuit (the "chip") & to found the Intel Corporation.


(+) Plate

(-) Shield

Control Grid

(-) Cathode

Heater

Inert Gas

Tetrode TubeControl Grid: Controls amplification rate & electron flow with bias voltage.

Shield: Screen grid- increases electron speed cathode to + plate.

Heater: Heats gas to gas amplification state.

Inert Gas: Mercury or Argon gas.


Cathode Ray Tube (CRT)

(+) Anode(-) Cathode

3 Electron Beams (Red, Green, Blue)

GridsPhosphor

CoatedScreen

ConductiveCoating

The cathode is a heated filament (like light bulb filament) in a vacuum inside a glass tube. The ray is a stream of electrons that naturally pour off a heated cathode into the vacuum. The + anode attracts the electrons pouring off the cathode. In a TV's CRT, the stream of electrons is focused by a focusing anode into a tight beam and then accelerated by an accelerating anode. This tight, high-speed beam of electrons flies through the vacuum in the tube and hits the flat screen at the other end of the tube. This screen is coated with phosphor, which glows when struck by the beam.


Bipolar Transistors

•History–Created in 1948 in the AT&T Bell Laboratories.–Scientists were performing doping experiments on semiconductor material (diodes) and developed a semiconductor device having three (3) PN junctions.


• NPN / PNP Block Diagrams

Bipolar Transistor Construction

Emitter

Emitter

N P N

P N P

Collector

Base

Base

Collector


• For any transistor to conduct, two things must occur.The emitter - base PN junction

must be forward biased. The base - collector PN junction

must be reverse biased.

Bipolar Transistor Theory


+ N P NEmitter

Base +

-

FB RB

Bipolar Transistor Biasing (NPN)

Collector


P N PEmitter Collector

Base

+

+

-

FB RB

Bipolar Transistor Biasing (PNP)


Bipolar Transistor Operation (PNP)•The + emitter repels the majority current carriers towards the emitter - base PN junction.

•Majority current carriers pass through the forward biased emitter - base junction and flow into the base. Once in the base, these current carriers now become minority current carriers and are attracted to the strong negative voltage applied to the collector.

•90% of the current carriers pass through the reverse biased base - collector PN junction and enter the collector of the transistor.

•10% of the current carriers exit transistor through the base.

•The opposite is true for a NPN transistor.


• The transistor below is biased such that there is a degree of forward bias on the base - emitter PN junction.

• Any input received will change the magnitude of forward bias & the amount of current flow through the transistor. The magnitude of the output will be on the order of 1000x larger depending on the value of +VCC.

Amplifier Operation

RB

RC

Q1

+

0

+VCC

Input Signal

+

0

Output Signal


Amplifier Electric Switch Operation•When the input signal is large enough, the transistor can be driven into saturation & cutoff which will make the transistor act as an electronic switch.•Saturation - The region of transistor operation where a further increase in the input signal causes no further increase in the output signal.•Cutoff - Region of transistor operation where the input signal is reduced to a point where minimum transistor biasing cannot be maintained => the transistor is no longer biased to conduct. (no current flows)


Amplifier Electric Switch Operation–Transistor Q-point

•Quiescent point : region of transistor operation where the biasing on the transistor causes operation / output with no input signal applied.

–The biasing on the transistor determines the amount of time an output signal is developed.

–Transistor Characteristic Curve•This curve displays all values of IC and VCE for a given circuit. It is curve is based on the level of DC biasing that is provided to the transistor prior to the application of an input signal.

–The values of the circuit resistors, and VCC will determine the location of the Q-point.


Transistor Characteristic Curve

IC

VCE

Q-Point

IB

0 uA

10 uA

20 uA

30 uA

40 uA

50 uA

60 uA

70 uA80 uA90 uA

Saturation

Cutoff


• When troubleshooting transistors, do the following:

– Remove the transistor from the circuit, if possible.

– Use a transistor tester, if available, or use a digital multimeter set for resistance on the diode scale.

– Test each PN junction separately. ( A “front to back” ratio of at least 10:1 indicates a good transistor).

Transistor Maintenance


Transistor Maintenance Chart

•This chart shows the readings for a good transistor.Test Lead

Connection( + / - )

NPNResistance Reading

(High / Low)

PNPResistance Reading

(High / Low)Base - Emitter LOW HIGH

Emitter - Base HIGH LOW

Base - Collector LOW HIGH

Collector - Base HIGH LOW

Emitter - Collector HIGH HIGH

Collector - Emitter HIGH HIGH

Transistor Maintenance


Transistor Maintenance Chart

•Advantages of junction transistors over point contact transistors:

-Generate less noise.

-Handles more power.

-Provides higher current and voltage gains.

-Can be mass produced cheaply.


Questions

Q) What is the 7 step troubleshooting method?

A) Symptom recognition, symptom elaboration, list possible faulty functions, identify faulty function, identify faulty component, failure analysis, repair, retest.

Q) What was the most difficult problem you ever troubleshot?

A) Various


Bipolar Transistor Amplifiers

•Amplifier Classification–Amplifiers can be classified in three ways:

•Type (Construction / Connection)–Common Emitter

–Common Base

–Common Collector

•Bias (Amount of time during each half-cycle output is developed).

–Class A, Class B, Class AB, Class C

•Operation–Amplifier

–Electronic Switch


Common Emitter Schematic

RB

RC

Q1

+

0

+VCC

Input Signal

+

0

Output Signal

Output Signal Flow Path

Input Signal Flow Path


• DC Kirchoff Voltage Law Equations and Paths

Kirchoff Voltage Law

RB

RC

Q1

+VCC

Base - Emitter Circuit

ICRC + VCE - VCC = 0

IBRB + VBE - VCC = 0

Collector - Emitter Circuit


Common Emitter Operation

Positive Going Signal

Negative Going SignalOutput Signal

Input Signal

+

+

0

0 Base becomes more (+) WRT Emitter FB IC VRC

VC VOUT ( Less + )

Base becomes less (+) WRT Emitter FB IC VRC

VC

VOUT ( More + )

RC

RB

Q1


Common Base Schematic

+

0

+

0+VCC

RBRCRE

Q1

CC






+VCC

RBRCRE

Q1

CC

Base - Emitter CircuitIBRB + VBE + IERE - VCC = 0

Collector - Emitter CircuitICRC + VCE + IERE - VCC = 0


Common Base Operation


Negative Going Signal

+VCC

RBRCRE

Q1

CC

Base becomes more (+) WRT Emitter FB IC VRC

VC

VOUT ( More + )

Base becomes less (+) WRT Emitter FB IC VRC

VC VOUT ( Less + )Input

Signal

0Output Signal

+

0


Common Collector Schematic

RB

RE

Q1

+

0

+VCC

Input Signal +

0

Output Signal






RB

RE

Q1

+VCC

Base - Emitter CircuitIBRB + VBE + IERE - VCC = 0

Collector - Emitter CircuitICRC + VCE + IERE - VCC = 0


Common Collector Operation


Negative Going Signal

RB

RE

Q1

+VCC

Base becomes more (+) WRT Emitter FB IE VRE

VE

VOUT ( More + )

Base becomes less (+) WRT Emitter FB IE VRE

VE VOUT ( Less + )Input

Signal

0 0

+ +

Output Signal


AZAZA VOPINI & House of BEC

Av = Voltage Gain

Zo = Output Impedance

Ap = Power gain

Zin = Input Impedance

Ai = Current Gain

Av = Voltage Gain

Zo = Output Impedance

Ap = Power gain

Zin = Input Impedance

Ai = Current Gain

Common Common Common

B E C

Common Common Common

B E C


Transistor Bias Stabilization

•Used to compensate for temperature effects which affects semiconductor operation. As temperature increases, free electrons gain energy and leave their lattice structures which causes current to increase.


Types of Bias Stabilization

•Self Bias: A portion of the output is fed back to the input 180o out of phase. This negative feedback will reduce overall amplifier gain.

•Fixed Bias: Uses resistor in parallel with Transistor emitter-base junction.

•Combination Bias: This form of bias stabilization uses a combination of the emitter resistor form and a voltage divider. It is designed to compensate for both temperature effects as well as minor fluctuations in supply (bias) voltage.

•Emitter Resister Bias: As temperature increases, current flow will increase. This will result in an increased voltage drop across the emitter resistor which opposes the potential on the emitter of the transistor.


Self Bias Schematic

RB

RC

Q1

+VCC

+

=

Initial Input

Self Bias Feedback

Resulting Input

+

+

+

+

o o

o

o

VOUT


Emitter Bias Schematic

RB

RC

Q1

+VCC

+

o

VOUT

RE

++

+

+

-

-Initial Input

+

o

CE

DC Component

AC Component


Combination Bias Schematic

RB1

RC

Q1

+VCC

+

o

VOUT

RE

++

+

+

-

-Initial Input

+

o

CE

DC Component

AC Component

RB2


Amplifier Frequency Response

•The range or band of input signal frequencies over which an amplifier operates with a constant gain.•Amplifier types and frequency response ranges.

•Audio Amplifier–15 Hz to 20 KHz

•Radio Frequency (RF) Amplifier–10 KHz to 100,000 MHz

•Video Amplifier (Wide Band Amplifier)–10 Hz to 6 MHz


Class ‘A’ Amplifier Curve

IC

VCE

IB

0 uA

10 uA

20 uA

30 uA

40 uA

50 uA

60 uA

70 uA80 uA90 uA

Saturation

Cutoff

Q-Point


Class ‘B’ Amplifier Curve

IC

VCE

IB

0 uA

10 uA

20 uA

30 uA

40 uA

50 uA

60 uA

70 uA

80 uA

90 uA

Saturation

Cutoff

Q-Point


Class ‘AB’ Amplifier Curve

IC

VCE

IB

0 uA

10 uA

20 uA

30 uA

40 uA

50 uA

60 uA

70 uA

80 uA

90 uA

Saturation

Cutoff

Q-Point

Can be used for guitar distortion.


Class ‘C’ Amplifier Curve

IC

VCE

IB

0 uA

10 uA

20 uA

30 uA

40 uA

50 uA

60 uA

70 uA

80 uA

90 uA

Saturation

CutoffQ-Point


Amplifier Coupling Methods

•Direct: The output of the first stage is directly connected to the input of the second stage. Best Frequency Response - No frequency sensitive components.

•Impedance (LC) Coupling: Similar to RC coupling but an inductor is used in place of the resistor. Not normally used in Audio Amplifiers.

•RC Coupling: Most common form of coupling used. Poor Frequency Response.

•Transformer Coupling: Most expensive form coupling used. Mainly used as the last stage or power output stage of a string of amplifiers.


Direct Coupling Schematic

RB1

RC1

Q1

+VCC1

RB2

RC2

Q2

+VCC2


RC Coupling Schematic

RB1

RC1

Q1

+VCC1

RB2

RC2

Q2

CC

+VCC2


Impedance Coupling Schematic

RB1

Q1

+VCC1

RB2

RC2

Q2

CC

+VCC2


Transformer Coupling Schematic

RB1

RC1

Q1

+VCC1

RB2

RC2

Q2

+VCC2

T1


Silicon Controlled Rectifiers

•Silicon Controlled Rectifiers (SCR)

–Construction

•Block Diagram

Anode Cathode

Gate

P PN N

Left Floating Region


OPAMP Voltage Regulators

Vin Vout

-+


SCR Schematic

Anode Cathode

Gate


SCR Bias

Anode

Gate

P PN NCathode

-

FB FB

RB

+

+

•When the SCR is forward biased and a gate signal is applied, the lightly doped gate region’s holes will fill with the free electrons forced in from the cathode.


SCR Operation

•Acts as an electronic switch•Essentially a rectifier diode which has a controllable “Turn - on” point. Can be switched approximately 25,000 times per second.•Once the SCR conducts, the gate signal can be removed. The difference in potential across the anode & cathode of the SCR will maintain current flow.•When the voltage across the SCR drops to a level below the “Minimum Holding” value, the PN junctions will reform and current flow through the SCR will stop.


SCR Phase Control

•The term Phase Control refers to a process where varying the timing of the gate signal to an SCR will vary the length of time that the SCR conducts.

–This will determine the amount of Voltage or Power delivered to a load.


Unijunction Transistors (UJT)

•Construction: Originally called “Double-based Diodes.”

–“P” Type material doped into the “N” type base material.–Placement of the Emitter into the Base determines the voltage level (%) at which the the UJT fires.

•This % is called the “Intrinsic Standoff Ratio ( ).”–Once constructed, the Intrinsic Standoff Ratio cannot be changed.

•The actual voltage value at which the UJT fires is determined by the amount of source voltage applied.


UJT Block Diagram

Emitter

Base 2

Base 1

P N Emitter

Base 2

Base 1

Equivalent Circuit


UJT Schematic Symbol

Emitter

Base 2

Base 1


UJT No Operation

•When VE is less than or equal to the voltage base one to emitter requirement (VE - B1), the UJT will not fire.

Emitter

Base 1

Base 2

P N

++

-

+

No Current Flow

Depletion Region


UJT Operation

Emitter

Base 1

Base 2

P N

++

-

+

UJT Fires

VE > VE-B1

•When VE is more than the voltage base one to emitter requirement (VE - B1), the UJT will fire.


UJT Sawtooth Generator

R1

C1

Q1

E

B1

B2

VBB

SW1VOUT

C1 Discharge

C1 Charge


UJT Relaxation Oscillator

R1

C1

Q1

VBB

SW1

VOUT1

C1 Discharge

C1 Charge

RB2

RB1

VOUT2

VOUT3

VOUT2

VOUT3

+

+

+

VOUT1



•The output of the Oscillator can be used for sweep generators, gating circuit for SCR’s, as well as timing pulses for counting and timing circuits.


Lessons Learned

• Video Card ruined from ESD < 20 V (Improper Handling).

• Bad Inductor in a regulator detected with Huntron Tracker. Slightly different oval.


Summary• Q) What is the phase relationship between

input and output voltage in a common emitter circuit?

• A) 180 degrees.


Summary Continued• Q) What type of transistor bias uses both self

and fixed bias?

• A) Combination bias.

• Q) What is the frequency response range of an RF amplifier?

• A) 10Khz – 100, 000 Mhz.


4 . Silicon Bilateral Switch (SBS)a . Construction

A2A1

G

P PN

J1 J2

A2A1

G


b . Schematic Symbol

Anode 2 Anode 1

A2 A1

Gate


c . Characteristic Curve

V A2-A1

I (mA)

Holding Current (IHO)

Reverse Breakover Voltage

Forward Breakover Voltage

Breakback Voltage


d . Characteristics1 . More vigorous switching characteristic. V to

almost zero.

2 . More temperature stable.

3 . More symmetrical wave form output.

4 . Popular in low voltage trigger control circuits.

e . Theory1 . Lower breakover voltages than Diac. (+/- 8V is

most popular).

2 . SBS has more pronounced “Negative Resistance” region.

3 . It’s decline in voltages is more drastic after it enters the conductive state.


f . Operation1 . As shown below, if a zener diode is placed in the

gate circuit between “G” and “A1”, the forward breakover voltage (+VBO) can be altered to approximately that of the zener voltage (VZ).

a . -VBO is unaffected.

SBS

A2 A1

G


2 . Characteristic Curve

V A2-A1

I (mA)

Holding Current (IHO)

Reverse Breakover Voltage


Breakback Voltage


5 Silicon Unilateral Switch (SUS)a Construction

P PN NAnode Cathode

Gate


b . Schematic Symbol

Anode Cathode

Gate


c Theory1 Similar to the four (4) layer diode except the +VBO can

be altered by using the gate terminal voltage.

d Operation

V A-C-V A-C

I


Reverse Breakdown Voltage

Much greater than Forward Breakover Voltage


6 . Varactora . Construction

P N


b . Theory1 . For testing purposes, a front to back ratio of 10:1

is considered normal.

2 . The size of the depletion region in a varactor diode is directly proportional to the amount of bias applied.

a . As forward bias increases, capacitance (Depletion region) decreases.

b . As reverse bias increases, capacitance (Depletion region) increases.

3 . In the capacitance equation below, it is shown that only the distance between plates can be changed.

C = Akd

Where: A = Plate Areak = Constantd = Distance between plates


a . An increase in reverse bias increases the width of the gap (d) which reduces the capacitance of the PN junction and vice versa.

4 . Advantage: Allows DC voltage to be used to tune a circuit for simple remote control or automatic tuning function.

c . Operation1 . used to replace old style variable capacitor

tuning circuits.

2 . They are used in tuning circuits of more sophisticated communications equipment and in other circuits where variable capacitance is required.


3V 6V

20F 5F

P N P N

Depletion Region


A. Special Purpose Amplifiers1 . Differential Amplifier

a . Schematic Diagram

+ VCC

- VEE

RE

RB (1)

RC (1)RC (2)

RB (2)

Q1 Q2

VOUT

VIN (1) VIN (2)


b . Operation

+ VCC

- VEE

RE

RB (1)

RC (1)RC (2)

RB (2)

Q1 Q2

VOUT

VIN (1) VIN (2)

+ -

(+) / (-) ARE ASSIGNED BY WHICH VOLTMETER LEAD IS USED AS THE REFERENCE

+

0

+

0++ ++

+ +

- -

+

0

VOUT


1 . With the polarities shown previously:a . On positive going signal, Base of Q1 becomes more (+)

with respect to emitter => FB Q1 => ICQ1 => VRC1 =>

VCQ1 (less +). Since ICQ1

=> IEQ1 (IE = IC + IB) => VRE

=> Emitter of Q2 becomes less (-) with respect to Base => FBQ2 => ICQ2

=> VRC2 => VCQ2 (more +). Due to the

polarities assigned by our voltmeter, the difference between Q1 and Q2 is becoming less => VOUT (Negative Going).

b . On negative going signal, Base of Q1 becomes less (+) with respect to emitter => FB Q1 => ICQ1

=> VRC1 => VCQ1

(more +). Since ICQ1 => IEQ1

(IE = IC + IB) => VRE =>

Emitter of Q2 becomes more (-) with respect to Base => FBQ2 => ICQ2

=> VRC2 => VCQ2 (less +). Due to the

polarities assigned by our voltmeter, the difference between Q1 and Q2 is becoming larger => VOUT (Positive Going).


c . With the resulting output achieved, it can be said that a positive going input on the base of Q1 caused VCQ1 to be inverted => the base of Q1 is called the “Inverting Terminal.” Since the positive going input caused VCQ2 to increase in a positive direction, the base of Q2 is called the “Non-Inverting Terminal.”

d . If my voltmeter leads were changed, the output of the amplifier would also change. The Inverting and Non-Inverting terminals would also change.


2 . Operational Amplifiers (OPAMPS)a .Block Diagram (Basic)

DIFFERENTIAL AMPLIFIER

VOLTAGE AMPLIFIER

OUTPPUT AMPLIFIER

NON-INVERTING INPUT

INVERTING INPUT

+

-

+ vCC

- vEE

OUTPUT


b . Ideal OPAMP Characteristics1 . Infinite () Input Impedance

a Draws little or no current from source.

2 . Zero Output Impedance

3 . Infinite () Gain

4 . Infinite () Frequency Response

a Constant gain over any range of input signal frequencies.


c . Types of OPAMPS1 . Linear (Output is Proportional to Input)

a . Inverting

+

-VOUT

VIN

RF

R1

+

0

+

0

+

-


b . Non - Inverting

+

-VOUT

VIN

RF

R1 +

0

+

0

+

-


c . Summing

+

-VOUT

VIN1

RF

R5

+0

+

0+

-

VIN4

+0

VIN3

+0

VIN2

+0

VIN1

VIN2

VIN3

VIN4

R1

R2

R3

R4


d . Difference

+

-VOUT

VIN1

RF

+0

+

0+

-

VIN4

+0

VIN3

+0

VIN2

+0

VIN1

VIN2

VIN3

VIN4

R1

R2

R3

R4

VIN5 0+ R5

VIN5


2 . Non - Linear (Output is not Proportional to Input)

a . Comparator

+

-VOUT

VIN

+

0

+

0

+

--

VREF

VREF ATTACHED TO EITHER + OR - TERMINALS

(EXAMPLE SHOWS OUTPUT WITH VREF CONNECTED TO THE NON-INVERTING TERMINAL.)

(WAVEFORM WOULD BE INVERTED IF VREF WAS ATTACHED TO THE INVERTING TERMINAL)

VIN VREF

VOUT


b . Differentiator

+

-VOUT

VIN

RF

R1

+

0

+

0

+

-

C1


c . Integrator

+

-VOUT

VIN

R1

+

0

+

0

+

-

C1


Field Effect Transistors (FETs)

•Field Effect Transistor Types–Junction Field Effect Transistors (JFETs) (N and P Channel)

•JFETs are voltage sensitive devices that use voltage vice current to control output.

•Current does not flow through a PN junction; however, a PN junction is used to control the size of a channel and to control current flow.


N Channel JFET

Source Drain

Gate

N

P

PChannel

P

PP

P

N

Depletion Region

--

-

++


P Channel JFET

Drain

Gate

P

N

NChannel

N

NN

N

P

Depletion Region

--++

+


JFET Schematic Symbols

Gate Gate

DrainSource Source Drain

N - Channel P - Channel


JFET Characteristic Curve

Ohmic Region

Pinchoff Region

Avalanche Region

VSD

ID

0


JFET Operation Regions

–Ohmic Region: As VSD increases, Drain Current (ID) increases in a nearly linear manner.

–Pinchoff Region: As VSD increases, Drain Current (ID) remains constant.

–Avalanche Region: As VSD increases, Drain Current (ID) increases uncontrollably and control of the FET is lost.


JFET Operation

–The voltage applied to the gate of a FET is reverse bias in nature and determines the size of the channel.

–When gate voltage (VG) is large enough, the depletion regions touch and drain current (ID) is cut off (Channel is Pinched Off). This is called the “Pinchoff Voltage.”–With Gate Voltage (VG) held constant, as VSD increases, Drain Current (ID) increases and vice versa. This assumes that the FET is operating in the ohmic region of the characteristic curve.


JFET Operation

VG = 0

VG = 1

VG = 2

VSD

ID

0


MOSFETs

–Metal Oxide Semiconductor Field Effect Transistors (MOSFETs)

•MOSFETs where originally called “IGFETs” due to the insulated gate portion of the the FET’s construction. •MOSFETs are extremely susceptible to damage from electrostatic discharge.


Depletion Mode MOSFET

P

Source Gate Drain

Metal Oxide Layer

P

Source Gate Drain

N

N

- - ++ + + --


Depletion Mode MOSFET

Schematic Symbols

Drain

Gate

Source Drain

GateN - Channel

P - Channel


Depletion Mode MOSFET Curve

ID

VG

0


N Channel MOSFET Operation

•N Channel Depletion MOSFET Biasing / Operation•Negative (-) on the Source, Positive (+) on the Drain, and Negative (-) on the gate.•Negative (-) on the gate will induce positive ions in channel which creates an area within the channel where there are no majority current carriers. (Depletion Region)

•The amount of Gate voltage (VG) applied will determine the size of the channel thereby controlling the amount of current flow through the transistor.


P Channel MOSFET Operation•P Channel Depletion MOSFET Biasing / Operation

•Positive (+) on the Source, Negative (-) on the Drain, and Positive (+) on the gate.

•Positive (+) on the gate will induce negative ions in channel which creates an area within the channel where there are no majority current carriers. (Depletion Region)


•N & P Channel Depletion MOSFET Biasing / Operation

•Depending on the polarity of the gate voltage (VG) applied, the depletion mode MOSFET can be made to operate either in the depletion mode or enhancement mode.


Enhancement Mode MOSFET

Block Diagrams (N & P Channel)

P

Source Gate Drain

Metal Oxide Layer

Source Gate Drain

NN N P P

- + ++ + - --


Enhancement Mode MOSFET

Schematic Symbols (N & P Channel)

Drain

Gate

Source

GateN - Channel

P - Channel


Enhancement Mode MOSFET Curve

ID

VG

0


N Channel MOSFET Operation

•N Channel Enhancement MOSFET Biasing / Operation•The Depletion region Creates / “Enhances” channel formation.



P Channel MOSFET Operation

•P Channel Enhancement MOSFET Biasing / Operation•The Depletion region Creates / “Enhances” channel formation.



MOSFET Gate VoltageEffects of Gate Voltage (VG) on Channel formation

P

Source Gate Drain Source Gate Drain

NN N P P

- + ++ + - --


Common Source JFET Amplifiers

RG

RD

+VDD

G

S

D++

+

0

Input Signal

VOUT--


Common Gate JFET Amplifiers

RG

RD

+VDD

G

S D++

+

0

+

0

Input Signal

VOUT

-

-RS


Common Drain JFET Amplifiers

+

0

+

0

Input Signal

VOUTRG

RS

+VDD

G

S

D++

--


Lessons Learned• MOSFET ruined from ESD < 20 V static

electricity.• Computer laptop not working anymore

when soda spilled on keyboard.• Computer motherboard overheated when

cooling fan seized due to accumulation of dust over the years.

• New computer BIOS chip ruined upon installation because not using the proper tool.


Logic Circuits

A . Boolean Algebra1 . Developed by George Boolean, a 19th century

mathematician.a . His theories were used to develop an assembly of

gears and pulleys to be used to drive a grain elevator.

b . A Boolean expression is nothing more than a description of the input conditions necessary to get a desired output.


c . Theorem

1 . A rule concerning a simple relationship between variables.

d . Postulate

1 . A basic statement that is accepted as valid.

a . Only two statements are true.

b . X = 0 and X = 1

Theorems and Postulates


1 1. . Distributive Law. (Repeating)a . Example: A + (B * C) = (A + B) * (A + C)

or A*(B+C) = A*(B+C) = (A*B) + (A*C)2 . Double Negative Law.

a . A = A3 . DeMorgan’s Law

1 A + B = A * B or A*B = A + B

4. Law of Intersection

1. A(1) = A

2. A(0) = 0

5. Law of Union

1. A + 1 = 1

2. A + 0 = A

Laws and Theorems


f Logic Symbols (Gates)1 . Logical functions can be expressed in one of four (4)

ways.)

a . English Statement

b . Boolean Expression

c . Truth Table

d . Logic Symbol

2 . “AND” Gate

a . The “AND” function is considered to be logical multiplication.

b . Any multiplication symbol can be used to express the “AND” function. (X, *, ( )( ), etc)

Logic Gates


c . English Statement - A and B equals Z

d . Boolean Expression - A X B = Z, AB = Z, (A)(B) = Z, A*B = Z etc.

e . Truth table

f . Logic Symbol

A B Z

0 00

01

11 1 1

000

ZB

A

AND Gate


a . The “OR” function is considered to be logical addition.

b . English Statement - A or B equals Z

c . Boolean Expression - A + B = Z

d . Truth table

e . Logic Symbol

A B Z

0 00

01

11 1 1

110

ZB

A

OR Gate


4 . Inverter “NOT” gate

a . The “NOT” function is considered to be logical inversion.

b . English Statement - NOT “A” equals Z

c . Boolean Expression - A = Z

d . Truth table

e . Logic Symbol

A Z0

01

1

ZA

NOT Gate


5 . “NOR” gate

a . English Statement - NOT A or B equals Z

b . Boolean Expression - A + B = Z

c . Truth table

d . Logic Symbol

A B Z

0 00

01

11 1 0

001

ZB

A

NOR Gate


6 . “NAND” gate

a . English Statement - NOT A and B equals Z

b . Boolean Expression - A X B = Z, AB = Z, (A)(B) = Z, A*B = Z etc.

c . Truth table

d . Logic Symbol

A B Z

0 00

01

11 1 0

111

ZB

A

NAND Gate


7 . “XOR” gate

a . English Statement - A exclusively or’d to B equals Z

b . Boolean Expression - A + B = Z

c . Truth table

d . Logic Symbol

A B Z

0 00

01

11 1 0

110

ZB

A

XOR Gate


a . Logic - NAND logic

1 . Set = Clear = 1: This condition is the normal resting state and it has no change of the FF output state.

2 . Set = 0, Clear = 1: This will always cause the output Q to equal 1 where it will remain even after set returns to a 1 value.

3 . Set = 1, Clear = 0: This will always set the Q output to a logic 0. It will remain there until the clear in[put returns to a logic 1 value.

SET

RESET

Q

Q

SET RESET FF OUT

1

0

1

1

1

0 0

0

NO CHANGE (HOLD)

Q = 1

Q = 0AMBIGUOUS

FLIP-FLOP


4 . SET = CLEAR = 1: This condition tries to “Set” and “Clear” the FF continuously and can produce an ambiguous result. Do not use.

b . Logic- “NOR” logicSET

RESET

Q

Q

SET RESET FF OUT

10

1

11

0 0

0

NO CHANGE (HOLD)

Q = 0

Q = 1AMBIGUOUS

FLIP-FLOP


c . Set - Clear Flip Flop

1 . High Input Responding (Logic High)

SET CLEAR FF OUT

10

1

11

0 0

0

NO CHANGE (HOLD)

Q = 1

Q = 0AMBIGUOUS

SET

CLEAR

FF

Q

Q

FLIP-FLOP


2 . Low Input Responding (Logic low)

SET

CLEAR

FF

Q

Q

SET CLEAR FF OUT

1

0

1

1

1

0 0

0

NO CHANGE (HOLD)

Q = 1

Q = 0AMBIGUOUS

FLIP-FLOP


d . JK Flip - Flop

1 . Logic Symbol

J

K

FF

Q

Q

CLK

PS

CLR

FLIP-FLOP


2 . Truth Table

PRESET CLEAR CLOCK J K Q Q

0 0 X X X 1 1

0 1 X X X 1 0

1 0 X X X 0 1

1 1 0 0 Q Q

1 1 1 0 1 0

1 1 0 1 0 1

1 1 1 1 TOG GLE

1 1 0 X X Q Q

INPUTS OUTPUTS

FLIP-FLOP


Bipolar Integrated Circuit Logic


Resistor - Transistor Logic (RTL)


Diode - Transistor Logic (DTL)


High - Threshold Logic (HTL)


Transistor - Transistor Logic (TTL)


Direct - Coupled Transistor Logic (DCTL)


Emitter - Coupled Transistor Logic (ECTL)


Integrated Injection Logic (IIL)


Oscillating Circuits


1 . Tickler (Armstrong) Oscillatora . Schematic Diagram

VCC

RC

RERBCB CE

C1

Q1

T1

OUTPUT

FEEDBACK L1

NPN1 3

2 4

Transistor Oscillators


b. Physical Description1 .) Uses an LC tuned circuit to establish the base

frequency.2 .) Feedback accomplished by mutual inductance

coupling between the tickler coil and the LC tuned circuit.

3 .) Uses class “C” amplifier with self - bias. c . Operational characteristics

1 .) Output frequency relatively stable.2 .) Output amplitude is relatively constant.3 .) RF frequency range4 .) Local Oscillator in receivers.5 .) Source in signal generators.6 .) Radio - frequency oscillators in the medium and

high frequency range.

Tickler (Armstrong) Oscillator


Schematic Diagram

VCCC3

CE

C1

C2

RB

RE

L2

L1

Q1

OUTPUT

Hartley Series Fed Oscillator


b .) Physical Description1 .) Can generate a wide range of frequencies and is easy to

tune.

2 .) Current Flows through the tank circuit in the series-fed, but not used in the shunt fed.

c .) Operational Characteristics1 .) Ordinary Operation: Class “C” amplifier with self-bias.

2 .) When output waveform must be constant voltage of a linear wave shape => Class “A” amplifier is used.



d .) Operation (Voltage applied to circuit)1 .) Current flows from battery (VCC) through L3 from collector

to emitter, through RE, through L1, and back to the battery.

2 .) The surge of current through coil L1 induces a voltage in L2 to start tank circuit oscillations.

3 .) When current first starts to flow through coil L1, the bottom of L1 is negative with respect to the top of L2.

4 .) The voltage induced into coil L2 makes the top of L2 positive.

5 .) As the top of L2 becomes positive, the positive potential is coupled to the base of Q1 via C1.

6 .) An increasing (+) on the base of Q1 causes forward bias to increase => IC increases => IE increases => IL1 increases and results in more energy being supplied to the tank circuit which in turn increases the (+) at the top of L2 and increases the forward bias on Q1.



7 .) This action continues to raise and lower the potential on the base of Q1 to control the output current.

a .) L1 feeds the tank circuit with energy that is lost during normal operation. (REGENERATIVE FEEDBACK).

b .) L2’s magnetic field expands and collapses to maintain current flow in the same direction. (Lentz’s Law)

c .) L3 develops the output voltage.



Schematic Diagram

C2

C1

C3

L1

CERE

RB

Q1VCC

L2 (RFC)

Colpits Oscillator


b . ) Operational Characteristics1 .) Both the Armstrong and Hartley can be unstable in

frequency due to inter-junction capacitance.

2 .) The Colpits has good frequency stability, is easy to tune, and can be used over a wide range of frequencies.

3 .) The large value of split capacitance (C1/C2) is in parallel with the PN junction and minimizes the effect of inter-junction capacitance on frequency stability.

4 .) Two capacitors are used in the tank circuit instead of a center tapped transformer.

5 .) can change the frequency of oscillation either by changing the capacitance or inductance values.

6 .) No coupling capacitor is used.

7 .) Voltage across C2 is used as the regenerative feedback.

Colpits Oscillator


5 . Piezoelectric Effect “Crystals”- A crystal is used as a frequency determining device

and can act in both series and parallel tuned circuits.

- Crystals used in oscillator circuits are thin sheets, or wafers, cut from natural or synthetic quartz and ground to a specific thickness to obtain the desired resonant frequency.

- Crystals are mounted into holders which support them and provide electrodes by which a voltage is applied.

- The holder must allow the crystals freedom for vibration.

Piezoelectric Effect


a . Theory

ELECTRODES

QUARTZ CRYSTAL

EQUIVALENT CIRCUIT

CP

CS

R

L

CRYSTALS


CAPACITIVE INDUCTIVE CAPACITIVE

FREQUENCY

SERIES RESONANCE PARALLEL RESONANCE

IMP

ED

AN

CE

FREQUENCY RESPONSE OF A CRYSTAL UNIT


b . Theory1 . Property of a crystal by which mechanical forces

produce electrical charges and, conversely, electrical charges which produce mechanical forces.

2 . Voltage applied to a crystal produces mechanical vibrations which, in turn, produce an output voltage at the natural frequency of the crystal.

3 . Crystals have a much higher frequency stability than an LC circuit => they’re used in sine - wave generators.

4 . Crystals are capable of producing highly stable output at a precise frequency.

5 . Crystal types:

- Quartz

- Rochelle Salt

- Tourmaline

CRYSTALS


Schematic

RB RE

RF

RC

CE

C1

C2

COUT

Y1VCC

Q1

Crystal Controlled Pierce Oscillator


Q 1

Q 2

Q 3

Q 4

Q 5

Q 6

Q 7

Q 8

Q 9

Q 10

Q 11

Q 12

C

RU306D S Q

C Q

R

D S Q

M305B

C R

A>B U300

A=B

A0

AB U301

A2

A3

A=B

AB

B2 A=B

B3 AB U302

A=B

A<B

A0

A1

A2

A3 A=B

B0

B1

B2

B3

S300

U304 +12V

Q1

Crystal Controlled IC Chip Oscillator


R1

R2

C

Simple SCR Gate Control Circuit

R1

R2

C R3

Improved SCR Gate Control Circuit

R1

R2

C1

R3

Improvement to SCR Gate Control

Circuit in “B” above

R1

R2

C

SCR Gate Control Circuit using a

Four-Layer Diode

C2

A B

C D

Semiconductor Gating Circuits


+10V


C1

R1

R2 R3

R4

Q1

VOUT1

VOUT2

VOUT3


Summary• Q. What solid state component in the UJT

Oscillator is used for wave shaping?

• A. Capacitor


Monostable (One Shot) Multivibrator

+VBB

-VCC

R1 R2R3

R4

R5

C1

C2Q2

Q1

0

0-

-INPUT

OUTPUT

Multivibrators


1 .) Usesa .) Used for pulse stretching

b .) Used in computer logic systems and Communication / Navigation systems.

2 .) Operational Characteristicsa .) +VBB is connected to the base of Q1 which places Q1 in

cutoff.

b .) Q2 is saturated by -VCC applied to its base through R2.

c .) C1 is fully charged maintaining approximately -VCC on the base of Q2.

d .) A negative gate signal is applied to the base of transistor Q1 which turns Q1 on and drives it into saturation.

e .) The voltage at the collector of Q1 is then attached to the base of Q2 which turns Q2 off.

f .) C1 is discharged to attempt to keep VC at Q2 constant. This maintains Q2 off.

Monostable Multivibrator


g .) When C1 is discharged, it can no longer keep Q2 off.

h .) Q2 turns on and saturates which causes its VC to go to approximately 0V.

i .) This 0V is applied to the base of Q1 which turns Q1 off.

j .) Q1’s VC goes to -VCC and C1 charges to -VCC.

k .) The multivibrator will remain in this original state until another gate “triggering” pulse is received.

l .) Output from the circuit is taken from Q2’s collector.

m.) Only one trigger pulse is required to generate a complete cycle of output.

Monostable Multivibrator


b .) Bistable (Flip - Flop) Multivibrator

+VBB

-VCC

R5

R2

R3 R4

R1C1 C2

Q2Q1

0

0

-

-

INPUT

OUTPUT 2

OUTPUT 1 R6

-

0

C3 C4

Bistable Multivibrator


1 .) Physical Descriptiona .) Multivibrator that functions in one of two stable states as

synchronized by an input trigger pulse.

2 .) Operational Characteristicsa .) Circuit is turned on.

b .) One of the two transistors will conduct harder and thereby reach saturation first. (Assume Q2)

c .) The 0V at the collector of Q2 is coupled to the base of Q1 which drives Q1 into cutoff.

d .) The -VCC at the collector of Q1 is coupled to the base of Q2 holding Q2 in saturation.

e .) An input trigger pulse is applied to the bases of both Q1 and Q2 simultaneously. Since Q2 is already in saturation, there is no effect on Q2.



f .) The trigger pulse turns on Q1 and drives the transistor into saturation.

g .) The 0V on the collector of Q1 is coupled to the base of Q2 driving Q2 into cutoff.

h .) The -VCC on the collector of Q2 is coupled to the base of Q1 holding Q1 in saturation.

i .) This process will continue as long as there are trigger pulses applied to the circuit.

j .) The output frequency of the waveforms will be determined by the frequency of the input trigger pulses.



c .) Astable (Free - Running) Multivibrator

-VCC

R1

Q2Q1

0

-

OUTPUT 2

OUTPUT 1 R4

-

0C2

R2 R3

C1

Astable Multivibrator


1 .) Physical Descriptiona .) Circuit has two outputs but no inputs.

b .) R1 = R4, R2 = R3, C1 = C2, Q1 & Q2 are as close as is possible in their operating characteristics.

2 .) Operational Characteristicsa .) Circuit is turned on.

b .) Assume that Q2 conducts harder than Q1 and goes into saturation first.

c .) The 0V at the collector of Q2 is coupled to the base of Q1 which drives Q1 into cutoff.

d .) C2 begins to charge. C1 is at -VCC and this voltage is applied to the base of Q2 to hold Q2 in saturation.



e .) After a finite period of time, (as set by the RC time constant of C2 and R3), C2 reaches a voltage value sufficient to snap Q1 on.

f .) Q1 quickly goes into saturation. The change in voltage from -VCC to 0Vcauses C1 to discharge.

g .) This voltage is coupled to the base of Q2 Placing / holding Q2 in cutoff.

h .) C1 begins to charge and will snap Q2 on when a sufficient voltage value is reached.

i .) In Summary, whenever a transistor saturates, its VC will change from -VCC to 0V. This voltage will then be coupled to the base of the other transistor which will drive the other transistor into cutoff. The frequency of the output waveform will depend on the RC time constants established at C1R2 and C2R3.

Documents

Fundamentals of Electricity & Electronics