And even at best the interpretation of test results are very subjective.Actually lie detectors are inaccurate because a knowledgeable tester can manipulate the subject and a knowledgeable subject can manipulate the test. Last time I checked lie detector tests were inadmissible as evidence in US court because the test is so easily manipulated.
Interesting read. Did you notice all the exemptions from this law, nearly all government and military are not restricted in anyway from using polygraph testing.
The cap is probably not necessary. Human bodies will generally have a lot of common-mode mains-related voltage (primarily 50 or 60Hz, depending on where you live), but this is relative to earth ground. I don't think there will be enough differential-mode noise to drive the transistor into saturation on the peaks, which would screw up the bridge. The cap is probably cheap insurance though, just in case.Hey guys I have a question was hoping could be answered. I'm an EE undergraduate student so I have been exposed to many type of transistor circuits.
Can you tell me what role the capacitor plays in this circuit? I do not understand why there needs to be a capacitor connected in between the two electrodes.
Of course it doesn't really work, it's a skin resistance meter, that's all - it will only detect is the person sweats when he lies.Any comments if it really works fine? It seams to simple to really work well detecting lies, but it could be possible if the lier is a big one and the person is very nervous.
Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring skin resistance, which goes down when you lie.