Help wid the simple lie detector

[umer007]

The attachd file is the schematic i got from the project ideas thread, it is the simple lie detector. I just wanted to ask wt kind of resistance shud i use for the resistors and wt capacitor to use. Also plz tell me wt that M1 is. And instead of electrodes will it still work if i just touch the skin with the end of a wire.

 

[grrr_arrghh]

hi

i've never got round to trying it out, but the M1 is an ammeter (if you look on google you can find circuits to replace ammeters with a circuit that has 2 or 3 LEDs)

try the values. i'd guess 100nF, 1uF or 10uF for the cap, and try the variable res at 100K, you can always vary it down if it is too much. The fixed resistor - something like 4.7K or 10K

lol, i don't really know - just try it and see what happens!!

Tim

 

[umer007]

yea i will try it. thx for the help.

 

[umer007]

o and btw, can neone help me find a circuit that can replace ammeters which uses LED's. I seearchd on google but cant seem to find one maybe bcuz i havent seen one b4 and dont xactly know wt to look for. I will continue searchin but if neone can find it plz post.

TYVM

 

[vaineo]

Well this one doesn't work with leds but you can try and addapt it, currently it works with varying clicking speeds depending on your galvic skin resistance.
If you want to use a wire instead of a pad you might want to add a piece of bigger copper on it so there more contact with the skin.

Part Name Part Qty.
500K Varitable Resister R1 1
100K Resister R2 1
470K Resister R3 1
.022 uF Ceramic Disc Capacitor C1 1
47uF Electrolite Capacitor C2 1
SPDT Switch SW1 1
Speaker 4 to 45 Ohms SP1 1
LM555 Timer IC U1 1
9 Volt Battery Connector N/A 1
Touch Pad N/A 2