Electroluminescent Logo Cap Project

Team # 10Milestone # 3 –System-Level Design Review

Faculty Advisor/Reviewers:Dr. Michael FrankDr. Bing KwanDr. Rajendra Arora

Team Members:Monica PereiraMonique PeregrinaLiang LiufuIfedayo Ogundana

Sponsored by:

Albert Daci

Monica Pereira

2Introduction/Overview of the Project

• The purpose of this project is to design an original cap that implements electroluminescent technology. This cap will consist of a panel with flashing capabilities and with a hidden internal circuit.

• Each cap will implement a switch with three states (turn on, flash, turn off) and be provided with an internal circuit with water resistant capabilities. In addition, the cap will come with a micro-USB charger hidden underneath the bill of the cap.

3

ADDITIONAL CONCEPT GENERATION & SELECTION

Monica Pereira

4Prototype ConceptFront View Internal View

Monica Pereira

5Overall Design Components

• Fitted baseball cap• LiPo rechargeable

battery • Battery charger• 10cm x 10cm EL panel• 3V DC battery inverter• IC chip• Liquid Encapsulating

epoxy resin

Reference No.

Description Component fulfilling this requirement

REQN-001   

The design must be able to light on, blink and turn of.

Timing IC

REQF-002 Use slim batteries that maximize the prototype efficiency

Li-Po rechargeable battery & battery charger

REQN-004  

REQN-006

Components will be water resistant  Design will withstand common wear and tear. 

Epoxy resin encapsulating material

CAP-001    

REQF-004

Panel must be able to turn on continuously, blink and turn off. A miniature button switch should be implemented in the bill to turn on/flash/turn off the EL logo.

Blinking will be fulfilled through the timing IC  The three operating modes will be operated through the single pole, triple-throw switch

Monica Pereira

6

Component selectionThe following components have remained the same:

PRT-00339 Lithium Polymer Battery

Item SpecificationsNominal Capacity

1000 mAh

Nominal Voltage

3.7V

Standard Discharge Current

0.2A

Max Discharge Current

2.0 A

Cell Voltage 3.7-3.9 VWeight Approx.: 20g

Monica Pereira

7

Parameter Value

Regulated output voltage

4.20 V

Temperature range -40ºC to 85ºC

PRT-00339 Lithium Polymer micro-USB Battery Charger

The LiPo Charger Basic uses a Microchip MCP73831T-2ACI/OT charge management controller to charge 3.7V Li-Po batteries at a rate of 500mA per hour.The board incorporates a charging circuit, status LED, connector for your battery (JST type), and USB connector. A small mounting hole allows this charger to be embedded into a project easily. 

Monica Pereira

8

Intersil LM555 timer IC• Specifications• Type: 555 type, Timer/Oscillator

(Single) • Supply Voltage: 2 V ~ 18 V• Current: 60µA• Operating Temperature: 0ºC to

70ºC • Max Frequency: 1 MHz

Monica Pereira

9Waterproofing/Insulating component Selection

Liquid Encapsulating Epoxy Resin

Color BlackCure Cycle 24 hDielectric Strength 19.36 kV/mLPot Life 60 minutes

Reasons it was selected:• Excellent electrical insulation

properties • Good storage stability • Supports high temperatures

10

Altered Selections

Monica Pereira

11

Specifications EL panelGlow size 10cm X 10cm

(3.95" x 3.95")Panel lifetime Greater than

25000 hoursOperating voltage

60-250V AC

Operating frequency

50-5000 Hz

Current Draw 0.14mA/cm2 (max) @ 110V / 400Hz

Initial Brightness 75 cd/m2

Operating Temperature

-50ᵒ C / 65ᵒ C

Panel Capacitance

45nF

EL Panels EL Panels from Surelight.com (Previous vendor was Adafruit)

Monica Pereira

12Battery Inverter

Weight 2.2g

Frequency 2500Hz

Power Supply Required

3V or 1.5V DC

3V ELI-IMC Battery Inverter

Previous OptionIn progress Approach:

Design our own inverter instead

13

SYSTEM DESIGN

Liang Liufu

14

Top Level Block Diagram

Liang Liufu

15

R1

150Ω

L1

3.518H

PanelC45nF

PanelR200Ω

Wien_Bridge_Oscillator

LM741CH

3

2

4

7

6

51

R3

398Ω

R4

490Ω

R5

398Ω

R6

1kΩ

C1

1µF

C3

1µF

V3

-3.7 V

555_Timing_IC

LM555CMGND

DIS

OUTRST

VCC

THR

CON

TRI

C40.1µF

RA1.0MΩ

RB220kΩ

CT1µF

C50.1µF

Switch

Key = Space Battery3.7 V

Timing_IC_Circuit

Oscillator_Circuit

Resonant_Circuit

Switch_Circuit

13

C21µF

Overall System Design

Liang Liufu

16

Requirements:• Input uses 3.7VDC• Output 110VAC• Output Current: >14mA• Output Frequency: 400Hz

Inverter Design

Liang Liufu

17

Wien-Bridge Oscillator Requirements• 3.7V input• 400Hz output• 20mA output

V1

3.7 V U1

LM741CH

3

2

4

7

6

51

R1

398Ω

R2

490Ω

R3

398Ω

R4

1kΩ

C1

1µF

C2

1µF

V2

-3.7 V

Vout

Inverter Sub-circuit: Oscillator

Liang Liufu

18

Output:•4.7Vp-p•27.6mAp-p•395Hz

Oscillator Simulation

Liang Liufu

19

Requirements:• Amplify oscillator signal to

achieve 110VAC• Maintain 400Hz• Output current of 14mAp-p

Inverter Sub-circuit: Resonant Circuit

Liang Liufu

20

Resonant Circuit Simulation

113VACp-p output12.1mAp-p output400Hz output

Liang Liufu

21

Overall Inverter Circuit

Liang Liufu

22Overall Circuit Simulation

110VACp-p Output14.1mAp-p Output395Hz

• In charge of controlling the blink pattern

• Will allow the logo to flash every second

• Uses a 555 Timing IC Specifications:• Power consumption: 15

mW• Input voltage: 3.7V• Output Voltage: 3.7V• Frequency: 1 Hz

Timing IC Subsystem

Monique Peregrina

555 Timing IC in Astable Mode

Monique Peregrina

Transient Analysis on the Timing IC

Monique Peregrina

26FULL CIRCUIT SIMULATION ON BLINK STATE

Monique Peregrina

RISK ANALYSIS

Monique Peregrina

28

• Battery Life DecreasedProbability: ModerateConsequence: ModerateStrategy

• El Panel Not Bright EnoughProbability: LowConsequence: Severe Strategy

• Timing IC Does Not Supply Enough Power Probability: LowConsequence: Moderate Strategy

Technical Risks

Monique Peregrina

• Disconnected WiresProbability: Moderate Consequence: DevastatingStrategy

• Moisture near Electronics Probability: Very HighConsequence: CatastrophicStrategy

• OverheatingProbability: Moderate Consequence: Moderate Strategy

29

• Tasks Assignment • Probability- high; Consequences- moderate• Strategy – Proper communication amongst members.

• Design dependencies• Probability- low; Consequences- moderate; Strategy- to be

set aside for help from advisor• Personal complications

• Probability- very low; Consequences – severe; Strategy – re-planning of task division

• Individual productivity• Probability- high; Consequences – severe; Strategy-

constant evaluation of individual progress

Schedule Risks

Ifedayo Ogundana

Ifedayo Ogundana

30

• More components may be neededProbability – moderate Consequence – minorStrategy – some funds are reserved

• Damaging the timer IC and/or the inverter Probability – low Consequence – severe Strategy – funds are reserved for purchase of extra major components

• Unaccounted-for-costs Probability- lowConsequence - moderate, Strategy – low price components are purchased and expenses are cut down

• Budget limitations Probability – low Consequence – moderate Strategy – component parts are ordered to together to reduce cost of shipping.

Budget Risks

Ifedayo Ogundana

31Updated BudgetCURRENT EXPENSES (CUSTOM

INVERTER)

Expenses Subtotal = $413.89 → $650.00 - $413.89 = $236.11 (Under budget)

Ifedayo Ogundana

32CURRENT EXPENSES (OFF-THE-SHELF INVERTER)

For off-the-shelf inverter:Expenses Subtotal = $446.34 → $650.00 - $446.34 = $203.66 (Under budget)

Ifedayo Ogundana

33

EL Cap BudgetUpdated Per-Unit Budget

Ifedayo Ogundana

34CURRENT EL CAP REPLICATION BUDGET (CUSTOM INVERTER)

35Updated Schedule

Monica Pereira

36

Thank You!Questions ?

Monica Pereira

37

EXTRA SLIDES FOR REFERENCE

38

Item Test Methods Performance  

Over charge

At 20±5°C charging batteries with constant current 3A to voltage 4.8V, then with constant voltage 4.8V till current decline to 0. Stop test until batteries temperature is 10 degrees lower than max temperature.

  

No explosion or fire

Over discharge At 20±5°C discharge battery with 0.2A continuously 12.5h. No explosion or fire

Short-circuit At 20±5°C connect batteries’ anode and cathode by wire which impedance less than 50mΩ, keep 6 h

No explosion or fire

 Thermal shock

Put the battery in the oven. The temperature of the oven is to be raised at 5±10 degrees per minute to a temperature of 130degrees and remain inside the oven 60 minutes.

 No explosion or fire

Safety TestTest conditions: The following tests must be measured at flowing air and safety protection conditions. All batteries must standard charge and lay 24h.

Li-Po Battery Performance

39

Cautions of charge & dischargeChargeCharging current should be lower than values that recommend below. Higher current and voltage charging may cause damage to cell electrical, mechanical, safety performance and could lead heat generation or leakage.Batteries charger should charging with constant current and constant voltage modeCharging current should be lower than (or equal to ) 1ACharging voltage must be lower than 4.25VDischargeDischarging current must be lower than (or equal to )2ADischarging voltage must not be lower than 2.75V.Over-dischargeIt should be noted that the cell would be at an over-discharge state by its self-discharge. In order to prevent over-discharge, the cell shall be charged periodically to keeping voltage between 3.6-3.9V.

40

Supply Current - Current in mA/cm2 versus supply voltage:

As the supply current is increased for the EL panel, the supply voltage also increases.

EL Panel Specs

41

Brightness Vs Timewith time.

Unlike most other lighting which can critically fail, EL Panel brightness decreases with time.

The following factors have an impact on lifetime:• Higher Voltage• Higher Frequency• DC Supply• High Ambient Humidity• High Ambient TemperatureBrightness can be increased by using a higher voltage or higher frequency.Higher voltage slightly decreases life time, but is preferred if higher supply current can be accepted.

42

EL Panels emit light from 50VAC and increase in brightness with higher voltage up to 200VAC. The frequency should be over 50Hz. Brightness increases with higher frequency up to 1000Hz. However, it is recommended that frequencies in the range of 400-600Hz and voltages of no greater than 160VAC are used, otherwise the panel life will rapidly deteriorate.

43

Timing IC and MOSFET Integration