How to Make a Lie Detector

Ever wanted to catch your friends lies? Its quite fun and works in most of the simple cases.
So here is the lie detector Tutorial. Its cheap and you can build under 20$ Lets Start.

Component List:-
1. Project Enclosure
2. 4.7K Resistor
3. 82K Resistor
4. 0.01uF Capacitor
5. 2N3904 Transistor
6. 2N3906 Transistor
7. 2-AA Battery holder
8. Small circuit board

Spare PC speaker, velcro, aluminum foil, wire and AA batteries in my extra parts bin. Also you will need glue gun, Soldering iron, soldering wire etc.

Here is the circuit diagram and you have to build the circuit like this. even if you are still noob in the electronics it wont be that tough to build it

After you have done with building the circuit, Put everything inside the project enclosure and take out the leads for the finger pad.
to make a finger pad. Follow this

Using a strip of Velcro (soft side), cut a piece of aluminum foil the size of the veclro. Make sure the velcro is long enough to go around a big, fat finger. Some liars are chubby. Remove the sticky side of the velcro and attach the aluminum foil with one of the Finger Pad leads under the aluminum. Then use a smaller piece of the other part of the velcro (the ‘hook’ side) and attach it to the end so the whole pad can be wrapped and secured.

Thats it. You are done.
The Detector we made works on the galvanic cell configuration. Learn some Electro-Chemistry to know its working, lol. But for the basics, when we lie , our skin gets bit moist , that the detector detects and notifies the lie. It is not accurate as the polygraph machine. But hey its enough accurate as for the cost of making (20$). So have Fun with it. In next article i will show you how to fake lie detectors

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