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Non contact voltage checker

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Tony 100

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Hi everyone (new user)

Need some help manufacturing a non contact voltage checker but are unable to find out what type of sensor is used in the "sniffing" of the voltage. I have tried an Hall effect sensor but this is not sufficient. anyone help?

Regards
Tony
 
A hall effect sensor will only work if current is present.
DC is hard to sensor at low voltages.
I assume you want to fine 120/220 volts A.C. 50/60hz.
I used an amplifier with very low input current like the LMC6442. Use high gain! Add some capacitors to make a band pass filter centered around 60hz. You need to remove high frequencies and DC. I used a 2 inch piece of heave wire or a 2x2 inch piece of copper as an antenna. I was able to find wires buried in the ground. I think with less gain you can find wires in a wall.
 
Best bet would be a combination of voltage detector and metal detector. If the wire has no electric field around it (unpowered) the metal detector will find it. To find low voltages you must cascade a lot of amplifiers to a gain of finally 1.000.000.000:1.

I did a circuit some decades ago indicating voltage walking on a carpet caused by friction. (that circuit used transistors) Use a twin circuit of low noise OpAmps, one for positive going voltage and another one for negative voltages or use dual power supply for one circuit. For detection use antennas as already posted here.
 
Mysterious sensor.

Hi Tony,

The mystery is solved, the sensor is nothing more than a 6n8
ceramic capacitor.

on1aag.
 

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on1aag said:
Hi Tony,

The mystery is solved, the sensor is nothing more than a 6n8
ceramic capacitor.

on1aag.


Hi
Can you tell me a little more about the theory behind the circuit, how does the Capacitor sense the presence of the supply
 
The capacitor is just an antenna. You could use a piece of copper. A metal button will work.

If you hold a metal frying pan close to an AC wire some energy will be transferred into the pan. (antenna)
 
ronsimpson said:
The capacitor is just an antenna. You could use a piece of copper. A metal button will work.

If you hold a metal frying pan close to an AC wire some energy will be transferred into the pan. (antenna)


Hi
Thank you for the information, what a great site with a great response. Thank you again, i will let you know how i get on.:) :)
 
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