Wednesday, February 13, 2008

TBs TechTOC 01 - Don't lie in front of your LEGO...

Don't lie in front of your LEGO (you may get caught lying...).

Believe it or not, it is not lie! ;)
Michael Gaspery made the lie detector below. Or putted into another way, a Galvanic Skin Response (GSR) sensor.
Rests to know whether it works accordingly...

This post intends to start a section for sporadic presentation of LEGO TECHNIC creations from others, which are commonly known as MOCs ("My Own Creation"). Here I a call them TOCs, because a funny expression I saw somewhere else, which stands for "Their Own Creation". ;)

You can see more details here.

"You can't get more simple than the Galvanic Skin Response GSR sensor. It is just a cut 9V LEGO motor wire and some aluminum foil wrapped around your fingers with tape.
It is popularly known as a lie detector, but is also used in Biofeedback conditioning. The theory is that; the more relaxed you are the dryer your skin is and so the higher the skin’s electrical resistance. When you are under stress your hand sweats and then the resistance goes down."

Take care! ;) Since the author finishes its article with the note below:
Warning: You should only use this sensor with an RCX running on battery power. Operation with the RCX plugged into a AC source could result in electrocution.


Alex Campos said...

"Warning: You should only use this sensor with an RCX running on battery power. Operation with the RCX plugged into a AC source could result in electrocution."

Why?! Electricity is harmful if either too much current flows through us, or if we're between two points at too different potentials (too much voltage).
In the former case, the RCX has current-limiting features for its outputs (that's why we can't hook up many motors into a single output). The same should apply to inputs: touch sensors short-circuit their terminals when pressed, and so the available current must be controlled.
In the latter case, the RCX receives only 9 V, which aren't harmful to humans: more than that can be obtained only by charging a pulse and then discharging it, like camera flashes. I don't see why the RCX would need to do it, since no motor or sensor needs high voltages.

TechnicBRICKs said...

Under normal circumstances or common failures, certain situations should never happen.

However there is always a probability for unlikely failures, that lead into extreme hazard.

After all a transformer is connected into a high voltage plug at one end, and to the RCX at the other. All the rest is just a matter of probability... ;)

Alex Campos said...

Anyway, I deeply believe the RCX would fry before its user did. ;-)

TechnicBRICKs said...

Not so sure, not so sure...

Certainly the RCX would fry! But would it be enough to prevent you from fry too?... ;)

Anonymous said...

I could not get the Lego lie detector to work. Is there some trick I am not aware of?

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