[prateeksikka]

I GOT THIS CIRCUIT OF A SIMPLE LIE DETECTOR AT WWW.AARONCAKE.NET BUT IT DOES NOT WORK PROPERLY NEITHER DO I KNOW HOW TO OPERATE IT.I HAVE ALREADY MADE IT.ANY SUGGESTIONS FOR IMPROVEMENT?
PRATEEK

View attachment 36622

 

[gsmaster1]

No cost Lie detector:
-Get ur multimeter, give to the person to hold the probes in each hand steady.
-Put the multimeter to the MOhm scale (usually 2Mohm is ok ) and you will see a value.
-If this value increases the person says the truth.
-If this value decreases the person LIES!!!

Basically it measures the resistence of the body. When a person lies, is stressed so the body temperature increases, so it gets more wet the resistance decreases.

 

[audioguru2]

Hi GS,
That's what a Chiropractor did when he measured my back for "computer analysis". Everywhere he pressed the ohm-meter probes harder, the computer showed that those locations on my back needed his very expensive "adjustments".
I should have put the probes on him to see how much he was lieing when he discussed a very expensive "treatment plan" for me.

 

[prateeksikka]

HI ALL!
SUGGESTIONS FOR RESOLUTION AND SENSITIVITY IMPROVEMENT IN THE CIRCUIT?
PRATEEK

 

[MP1]

Hi GS,
That's what a Chiropractor did when he measured my back for "computer analysis". Everywhere he pressed the ohm-meter probes harder, the computer showed that those locations on my back needed his very expensive "adjustments".
I should have put the probes on him to see how much he was lieing when he discussed a very expensive "treatment plan" for me.

Perhaps it was very sophisticated equipment to see if you were "Lying" on your back. ;D

MP

 

[gg4rest]

You may want to purchase some electrolytic gel to put on the electrodes (the kind used for electromyogram and electrocardiogram sensors). Medical supply stores should have this. This will reduce the contact resistance between the electrodes and the person's hand. That will allow more precise measurement of the resistance between the two electrodes.

Instead of a ammeter, you could use a resistor and connect it across a dfference amplifier's input leads. This will take the voltage across that resistor and amplify it. Then you just measure the output from the difference amplifier with a volt meter. The circuit is a little more complicated (1 IC and some resistors) but it should work.