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.

Step 1: 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!

Comments

[Titann123]

I can't seem to find a 47k ohm potentiometer, will a 50k still work? Please respond.
Email: [e-mail]

[Sandman.]

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?

[aaks]

What is the efficiency of this lie detector machine?

[mshbi]

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?

[m4a1carbine]

they don't have 47k ohm Potentiometer in our local electronics store. Will 50k ohm work?

[nox1468]

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?

[mykiscool]

Nice, I was just thinking of this idea!

[Asoom Chan]

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 * ^^

[rickharris]

variable resistor (a potentiometer)

[josephricafort]

So cool. I'm going to make one of these. Thanks for posting!

[raghav57]

is blue colour one vr and beside that red one is capacitor plese reply

[raghav57]

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

[AJMansfield]

You should make it zap them when it detects a lie.

[Nano robot]

How do you make the finger pad. It say put the wire between foil and Velcro.do you glue it or solder the wire. What kind of coil do we use for finger pad?

[Nano robot]

How to identify ardent of 47K trimmer ?

[Nano robot]

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

[Socco]

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.

[robot1398]

what do you mean by 0.1 mylar cap and 1M& resister x2

[static]

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.

[lespaul55]

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!!!

[lespaul55]

Its an extra cap that you don't need.

[robot1398]

hi

[noliver]

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

[paewookyung]

It means 'Variable resistor' or 'Volume resistor'.
Just get to your local electronic store and ask for it.
it'll probably available in most part of the world....

[Sohaib Asif]

is this real lie detector??????????????

[D1g1talAli3n]

Will a 50K VR work?

[D1g1talAli3n]

Will a 50K VR work at all?

[porcupine_malik99]

you are using two capacitor but in diagram there is only 1 capacitor? whre would da 2 one placed?

[Jimmy Proton]

He said in an earlier picture that the electrolytic capacitor is optional, if that helps.

[lespaul55]

What's the uF of the electrolytic capacitor?

[LiLGq]

um.....people.....can i ask a question about the 47VR he wrote there if it is a potentiometer so how much is the value?????....and another thing is what is a mylar cap????.....and how much is the correct value of it 'cause there are 2 caps there....the .1 and the 100..so which is the cap really used to this project???....

[mwagner63]

In the schematic it says 100nf

[LiLGq]

tnx....

[mwagner63]

Also I couldn't find the 100nf capacitor so I looked around and it is actually .1uf

[lespaul55]

Yes there are!!! ^^^

[isamuel]

what is this thing detecting?

[lespaul55]

I'm pretty sure the electrical pulse in you fingers. Generally speaking it increases when someone is lieing. I haven't made this design so I don't know the sensitivity of the readers.

[lespaul55]

What does VR stand for? Where do I get one?

[lespaul55]

Variable Resistor

[lespaul55]

What A is the switch and what is the round blue thing in the first picture?