Instructables

How to make a portable handy lie detector in Altoid tin

Step 3: Solding the circuit

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
 
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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?
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.
Will a 50K VR work at all?
SUBYRIDA253 years ago
Hi, Could you show the back of the circuit. I'm new to the electronics game and could use a little help. Thanks
kengelman3 years ago
can anyone show me what the back of the finished circuit board looks like?
robert0joe4 years ago
Can I use AA batteries instead of 9V? Like 2 AAs?
no..............but you can get some at pep boys in packs of 20!!!!!!!!!!!!
Can you split R4 into 2 resistors, 1 for each transistor emmiter?

I'm pretty sure that R4 is the LED resistor.
dwatord264 years ago
is this board printed or is a basic board like the ones bought at radio shack?
jho5 years ago
I am from colombia, and therefore does not expect to understand some English grammar mistakes. quisira whether the circuit diagram shown corresponds to the real lie detector, because according to the diagram, a non-polarized capacitor (the 100nF) in the photo while the circuit is completed and extends to probably see a polarized electrolytic capacitor. If so then this would not work first ...