How Do I Make a Homemade Polygraph Test?

Build Your Own Polygraph

• 1

  Connect the N3906 transistor to the N3904 transistor. Use wire and a soldering iron. First solder the wired connections and then glue the piece to the circuit board. Follow this procedure for all of the following pieces and connections. Make sure that all of the solder joints are secure before gluing.

• 2

  Add the 82K resistor to the wire between the two transistors. This is the only wire the resistor is connected to. Solder this resistor into place.

• 3

  Use more wire to solder another connection from the N3904 transistor to the 4.7K resistor. The 4.7K resistor then connects to the capacitor and the capacitor connects to the speaker using wires. Therefore, the connection sequence is N3904 transistor to 4.7K resistor to capacitor to speaker.

• 4

  Twist the wire that runs from the resistor to a terminal on the capacitor cap. Twist a second wire around the other terminal on the capacitor cap and run this to the speaker input terminal. Capacitors will have two terminals on the cap.

• 5

  Attach the appropriate speaker wire connector to the end of the wire and plug this into the speaker input terminal. The type of connector will depend on the speaker.

• 6

  Run a second wire from the N3906 transistor and connect this to the two AA batteries in sequence. The sequence of this connection is as follows: the second N3096 wire connects to one AA battery, and another length of the same wire connects the first AA battery to the second AA battery. Run another wire from the second AA battery to the speaker power input. You need a speaker wire connector to make the speaker connection. To connect the wires to batteries, use electrical tape and securely tape the wire to the ends of the batteries.

• 7

  Solder a third wire running from the N3904 transistor to the wire that runs from the second battery to the speaker.

• 8

  Solder a wire from the 82K resistor. Solder a second wire from the wire that is found between the 4.7K resistor and the capacitor. These wires should be long, as they will be connected to the finger pads. The length of the wires will depend on the dimensions of the box and where the person taking the test will be positioned relative to the box. For an individual sitting in front of the box, the wires should be at least 2 feet in length. For farther distances cut the wire longer. If necessary cut the wire and splice in additional length if needed.

• 9

  Secure the circuit board with the polygraph circuit into the box. Drill holes into the box and thread the finger pad leads through the holes.

• 10

  Cut two strips of aluminum foil and glue the foil to the Velcro. Make sure that the strips are long enough to circle a person's finger. One strip is for the forefinger and one is for the ring finger.

• 11

  Wrap the finger pads around a person's forefinger and ring finger on the same hand as close to the fingertips as possible. Ensure that the aluminum foil is in contact with the skin.

• 12

  Start asking questions. When a person is lying she will perspire more. This machine measures the moisture change in the skin of the fingers, also known as galvanic skin resistance. When the skin starts to sweat, or when a person is lying, the increased moisture transmits more electricity, which will turn the speaker on.