Sunday, March 9, 2014

A Portable lie-detector

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                                            A Portable lie-detector

This is a portable lie-detector built in a tin box . maybe you could have some fun using this thing.

Note : this detector is less sensitive then a real one. this could be miss some (many) of the lies.

Things you'll need.

You will need some things below for this project.

1. circuit board
2. 10K resister
3. 47K resister
4. 470 resister
5. 1M resister x2
6. 47K VR
7. knob for VR
8. 2N3904 transistor x3
9. 0.1 ? mylar cap
10. slide switch.
11. 9V bettery snap
12. LED (one red, one green)
13. solding tools.
14. drill
15. basic tools,
16. velcro (magic strip)
17. aluminum foil
....and most of all, a tin box 
Make a finger pad
make a finger pads by sticking a aluminum foil to the velcro (strip)
And don' forget to stick a wire between the velcro and the foil!

Soldering the circuit

Solder the circuit as a diagram below. And before soldering the circuit, cut the circuit board to

suitable size to fit in the tin

Drilling the Tin case

Drill the tin for a VR.

and DO NOT use a sharp-end drill bit. it will tear the tin into half

Put the floor sheet

Put the floor sheet in a floor of the tin to avoid it from 'short circuiting'.

and secure it with a glue.

in my case, I used a piece of box, and secure with a hot melt

Put everything in order

Put everything in the tin and secure all of them with a glue, hot melt, etc 


Now your lie detector is ready to go. first, put the finger pad to the finger of the 'suspect'
then, slowly, turn the VR until the 'true' LED is light, and the 'false' LED is dark.
then, ask a question to the suspect , when the false LED gets lighted, the suspect is lying