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 3: Solding the circuit

Picture of Solding the circuit
finished circuit 02.JPG
finished circuit.JPG
Solder the circuit as a diagram below. And before solding the circuit, cut the circuit board to

suitable size to fit in the Altoid tin

Step 4: Drilling the Altoid tin

Picture of 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.

Step 6: Put everything in order.

Picture of Put everything in order.
Put everything in a Altoid tin and secure all of them with a glue, hotmelt, E.T.C

Step 7: Done.

Picture of Done.
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 get light, the suspect is lying.
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sandhyaar12 days ago

HI.. this project looks quite simple.. But.. whats the assurance that it detects lie?? Can u please explain that perspective??

bwclark10117 days ago

I am sorry I mean, do you need the VR?

bwclark10117 days ago

Do you need to VR?

it's too much easy ... because i make it

hi bro...can u send me snap of ur project coz m crently working on this project???

KassidyGarvey2 months ago

I saw this back in October and wanted to do it for a school project so I went to radioshack and ace to try to find everything and ended up going to radioshack multiple times to get the parts. I built this with my dads help because i am new to circuits and we haven't been able to get it to work. the LEDs won't light up, we connected the LEDs to a wire and then to a 9 volt and they light up but then when we connected the 9 volt into the circuit nothing happened. can you maybe tell me what might have gone wrong? you can email me and i can send you pictures of what it looks like thank you!

did you connected leds to 9volts with or without the limiting resistor?, if without then your leds are probably toasted.

yhdesai1 month ago


sowmya.ganti2 months ago

where do we attach that knob in the circuit..??

the circuit is not so clear..!!

manolis.kasos3 months ago

Can sb explain the working of the electronics of this and if anybody has tested this and if it works

can we use subsitute for Altoid tin

Fission Chips5 months ago

Awesome project! Thanks for putting this on the site.

did this work for you

plzz post the block diagram

Will a 50K VR work at all?


NazyaT7 months ago

you can snd pictures ya video of you circuit backside and frontside how u have wireing u have did i cant understand plz snd me pic ya vdo

bmann9999 NazyaT4 months ago

i cant understand what you just wrote there...

Can you add a video also ?

in circiut diamgram mylar cap is not their

NazyaT7 months ago

in circiut diamgram mylar cap is not their

in circiut diamgram mylar cap is not their

joelhacks6 months ago

is there a space between the aluminum foil, or does it touch?

NazyaT7 months ago

from where u have get how to make lei dector

NazyaT7 months ago

how to use it it continuesly red light burning

plz hel me

NazyaT7 months ago

plz reply me

my brother

NazyaT7 months ago

i cant see wiring proper le

NazyaT7 months ago

i have made this as same circuit digram i have on the switch on and it continusly red coming and green light is not coming what can i do plz hel me brother

CRASH MA5TER8 months ago

about how much does this cost

0RUS09 months 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

forever56710 months 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?

mhannan211 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

kalmost131 year 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
raghav572 years 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
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...
tim90091 year 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?
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