PsychogalvanometerPART NO. 2180261

This Kit will show you how to build a basic PsychoGalvanometer using small number of components on a breadboard.

With the addition of probes and an audio output jack attached across the speaker, sensors can be placed on the leaves of plantsand the modulated square wave data stream can be brought into a computer for processing.

By translating these signals into MIDI, we are able to graph, through sound, a representation of the dynamic changing states withinplants.

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Time Required: 20 mins depending on experienceExperience Level: BeginnerRequired tools and parts: Wire Cutters, Wire Stripper, Soldering Iron, Solder

Bill of Materials:

Qty Jameco SKU Component Name1 2155452 Breadboard SmallSmall Breadboard, ideally with sticky foam tape on the bottom.1 216144 Battery Holder 3-AASwitched battery box1 2161537 Audio output JackOutput jack, switched if using a speaker in the build1 890091 NE555N Timer IC10 2156084 100K ResistorOnly one 100K Resistor is needed for this build10 138202 Capacitor .0047uF10 2157159 1K Resistor10 697573 LED3 2112444 Batteries 3x AABattery count depends on the battery case, this build uses 3 AA's, a 9v could be used1 76030 SpeakerA small speaker with wire leads or pin leads1 2110916 Jumper WireSmall, short jumper wires.

Step 1 - How It Works

This kit will show you how to build a basic psychogalvanometer using a small number of components on a breadboard.

This schematic shows a 555 timer setup as an astable multivibrator.

With the addition of probes and an audio output jack attached across the speaker, sensors can be placed on the leaves of plantsand the modulated square wave data stream can be brought into a computer for processing.

By translating these signals into MIDI, we are able to graph, through sound, a representation of the dynamic changing states withinplants.

Step 2 - The 555 timer IC

Step-1 Identify the 555 timer IC, it is the small square component.

Place the 555 timer such that pin 1 is at the top left corner, indicated by a small circle. (Some ICs also may have a notch at one end, thiswill also indicate pin 1 on an Integrated Circuit.)

Place the 555 in the 4th Row down from the top,line up one side of pins with holes in the breadboard, press pins on the other side into theholes with your finger. You may need to squeezeslightly, but be careful not to bend any of the pins!If you do, carefully bend them back.

Step 3 - Jumper Wire

Step 2a:

Your kit should contain jumper wire, which will either be single core or stranded, stripped at the ends and may be tinned with solder.

If you ever need jumper Wire, it is easy to salvage jumpers from old printer cables, ethernet, telephone almost any old smallgauge wire can be made into jumpers.

It is important to make clean cuts for your jumper wires. And a wire stripping tool makes things very easy!

Step 4 - Positive Voltage Jumper

Step 2:

Refer back to the schematic, we see pin 4 and pin 8 attach to positive voltage.

Attach a piece of jumper wire between pin 4 andpin 8 on the breadboard.

Step 5 - Positive Voltage Resistor

Step 3:

Refer back to the schematic, we see that the 100K resistor connects pin 7 (Discharge) to positive voltage.

Prepare the 100K resistor, bend one lead back around and trim the ends to 2 cm.

Place the bent 100K resistor leg in the rowcorresponding with pin 7 and pin 8, here the resistor is, from the top of the breadboard, In rows 4 and 5.

Step 6 - Negative Jumper

Step 4:

Refer back to the schematic, we see that pin 2and pin 6 are connected. Place a jumper wire between pin 2 and pin 6 on the breadboard.

Step 7 - LED Driver Resistor

Step 5:

Refer back to the schematic, we see that pin 3 Is connected to the LED through a 1K resistor.

Prepare the 1K resistor which will drive the LED,by bending its legs downward, cut to 2cm length.

Bend the resistor leads, connect to pin 3and to an empty row, here row 6 is pin 3and row 10 is the hot end of the driver resistor.

Step 8 - Ground Bus

Step 6:

In order to give us more room to work, a jumperis placed between pin 1 (row 4) and a lower holeon the breadboard (row 11). This brings ground from pin 1 (row 4) down to the cathode of the LED

Now it will be easy to place our LED, with the drive resistor and ground bus nearby!

Identify the LED, note the longer leg is the positiveSide which should connect to the resistor on pin 3

Step 9 - LED

Step 7:

Place the LED, with the longer leg (+ Anode) Connected to the 1K resistor in row 10.

Connect the shorter leg (- Cathode) to the ground bus in row 11

Step 10 - Capacitor and Probes

Step 8:

The capacitor has long leads which we will cutand use as touch point Probes to sensegalvanic changes.

Cut the leads as shown to 1cm from the cap.

Make 1 cm bends in each piece for the probes

Step 11 - Capacitor

Step 9:

Refer back to the schematic, we see that the junction of pin 2 and pin 6 goes to ground through the .0047 capacitor.

Place the capacitor between ground pin 1 (row 4) and pin 2 (row 5).

Step 12 - Probes

Step 10:

Place the bent leads cut from the capacitor onto the breadboard to act as probes.

When your finger is placed across these probes, the galvanic resistance of your skin will influence the pulse width, andcorresponding pitch, of the 555 timer.

Place one of the bent leads between pin 6 (row 6) and an open row (row 11).

Place the other bent lead between pin 7 (row 5) and an open row (row 9)

Step 13 - Power Connections

Step 11:

The battery holder should have a power switch integrated. Turn the switch to OFF, load up some batteries, and attach the red(positive voltage) and black (ground) wires to the breadboard.

The leads should come pre stripped and tinned, refer back to step 2a if you need to strip or tin the battery holder wires.

Place the red wire into row 4, corresponding with pin 8 to provide positive voltage.

Place the black wire into row 4, corresponding with pin 1 to provide ground.

Almost Done!

Step 14- Speaker Output

Step 12:

The rising and falling of the square wave pulse can be used to drive a speaker.

As galvanic conductance increases across the probes, pulse widths get smaller, and the perceived pitch increases.

Attach one of the wires leading from the speaker to ground at pin 1 (row 4).

Attach the other speaker wire to the ouput pin 3 (row 6)

Step 15 - Complete

Step 13:

All connections are now complete!

Push the power switch to the ON position, the LED should light up.

Dampen your index finger and gently place your finger across the probes on pin 6 and pin 7. You should hear a sound, and the LEDshould flash with each pulse!

Congratulations, you have built a PsychoGalvanometer!