How to make a portable handy lie detector in Altoid tin

Picture of How to make a portable handy lie detector in Altoid tin
Hi. I'm paewookyung, and this is my first posting in this site. please take note that
english is not my mother tongue. so please understand some of my gramatic mistake.;

Anyway, let's get this started!
This is a portable lie-detector built in Altiod tin. maybe you could have some fun useing this thing.

note: this detector is less sensitive then a real one. this could be miss some (many) of the lies.
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Step 1: Things you'll need.

Picture of 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. valcro
17. aluminum foil
....and most of all, Altoid tin!

Step 2: Make a finger pads

Picture of Make a finger pads
make a finger pads by sticking a aluminum foil to the valcro.
And don' forget to stick a wire between the valcro and thw foil!

Step 4: Drilling the Altoid tin

Drill the Altoid tin for a VR.

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

Step 5: Put the floor sheet

Picture of Put the floor sheet
Put the floor sheet in a floor of the tin to avoid circuit from 'shorting'.

and secure is with a glue.

in my case, I used a piece of box, and secure with a hotmelt.
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CRASH MA5TER21 hours ago

about how much does this cost

0RUS01 month ago

I put it together like shown on the schematic, but all I get is a constant red light, and when I turn the pot all the way the green LED starts to glow, bu just a bit, and red is still on.
If anyone can please help

forever5671 month ago

I built this schematic but I can't quite get it to tell weather your telling a lie. When I turn it on it only lights up green. How can i fix this problem?

mhannan23 months ago

Hi, can you explain how this circuit works ? I am taking it as my Basic Electronics Project . I want to know how it work ( how it detect lie). Plz reply me

kalmost134 months ago

Did this actually work for anyone? Because I don't want to waste my time on a frivolous idea.

Ima use it as my science project
Will a 50K VR work at all?
raghav571 year ago
i am raghav.i am 13 years old i understood everything but what is the thing up of slide switch or down of knob .plese reply
robo10302 raghav5711 months ago
hi raghav were you talking about the potentiometer or the perf board
plz say your email id i got every part its now working i think you can help me. my email id is
Can you explain how this works, the principle behind it pls...
tim900910 months ago
I am fairly new to electronics, so I am looking for schematics to learn from. I do have a question about this one. I tested it out in a circuit simulation program (iCircuit) and played around with it for a while. I tried to remove the capacitor and found that it worked just as well without it. What role does the capacitor play in the circuit? Can it be removed or is just a bug int the software I am using?
Sandman.1 year ago
I'm having a hard time finding a 47k ohm VR, the knob for it and the mylar cap. Anyone know a good place to buy these?
robo10302 Sandman.11 months ago
hi sandman where do you live?
pavan chowdary11 months ago
what is ment by vlacro
it sounds nice but i will be greatfull to u if u share ur ideas directy to me as i am fond of electronics
the experiment tells that when we lie our resistance will decrease n atomatically the sound will occur
some people will lie very confidently with out any fear
2 such lik people does this experiment will work?????
if no wats d advantage of using this lie detector?????
It will not work 2 such people. Only through EEG one can detect lies. this circuit is for fun
Titann1231 year ago
I can't seem to find a 47k ohm potentiometer, will a 50k still work? Please respond.
aaks1 year ago
What is the efficiency of this lie detector machine?
mshbi1 year ago
When I hooked mine up only the red LED lit up no matter how much I turned the variable resistor. Anyone know how to fix this? Also how does this lie detector work?
they don't have 47k ohm Potentiometer in our local electronics store. Will 50k ohm work?
nox14681 year ago
i seem to have a problem, the red light always stays on and the green one only turns on if i turn the potentiometer all the way to one side, and additionally it is unnafected by wheather someone is lying or not. any suggestions?
mykiscool1 year ago
Nice, I was just thinking of this idea!
Asoom Chan1 year ago
Can you please tell me what a VR is ?
I'm still new to this whole electronics thing :)
* And thanks for posting, it looks like a lot of fun * ^^
variable resistor (a potentiometer)
So cool. I'm going to make one of these. Thanks for posting!
raghav571 year ago
is blue colour one vr and beside that red one is capacitor plese reply
You should make it zap them when it detects a lie.
Nano robot2 years ago
How do you make the finger pad. It say put the wire between foil and you glue it or solder the wire. What kind of coil do we use for finger pad?
Nano robot2 years ago
How to identify ardent of 47K trimmer ?
Nano robot2 years ago
I brought a 100nf, can I use it for Mylar cap? And i brought a 1Mo resister,can i use it for 1M resister? Reply soon please
Socco2 years ago
err, your LEDs are incorrect on the schematic and should be swapped so that the L1/Green is on the left and L2/Red is on the right. Then, when the probes are squeezed (or put on tongue) to reduce their impedance the Red LED will light, as expected. I found this after building the circuit.
robot13983 years ago
what do you mean by 0.1 mylar cap and 1M& resister x2
In Stating the obvious a potentiometer IS a variable resistor, but identifying it as potentiometer is best. Because search for a variable resistor will bring an overwhelming items for beginners to consider. Beginners will be faced with choice between an audio/logarithmic taper (volume control) or a linear taper. No doubt for this project they would want a linear taper, although an audio taper would function.
WHAT IS THAT BLUE CYLINDER SHAPED THING? The skematic says its the VR but the vr is attached to that thing. I though it mught be the mylar cap but thats the red one. Please Help!!!
Its an extra cap that you don't need.
noliver3 years ago
47K& VR another 47k and whats a VR? cause i googled it and it came a 1,000,000 bucks and yes im an electrical navis plz reply soon
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