Amazon got me in an ad but this looks cool
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Non contact volt METER (not just test light) with an laser aimed IR thermometer. $40Cool electrical tool.
Oct 15, 2020
Last reply: 5 years ago
10 Replies
Would have been very hand over the years for many different circumstances.
I have no use for it, but I sure want one.
How is that possible?
Capacitive coupling to the changing AC fields. Note that it is a tester, not a meter. It will tell you AC is present; and may give you a rough estimate of the voltage.
It might be as accurate as a $5 Harbor Fright meter. I have one coming, I will let you know. I do have a variac that I can diddle the voltage from 0~250 and compare the reading to my Fluke meter.
Hall effect sensor for the AC voltage.
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That's one way to to it. Other designs use a FET on the front end or an op amp. Some add a 555 to get blinking lights.
That?s no good for a voltage reading rather than just voltage present.
Its not clear if that thing actually shows voltage values or just the temperature values.
The one the OP linked has a flashing red and blue LEDs to give a rough indication.
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Some of them light up for any AC voltage in their operating range, others try for a rough estimate. They're not DVMs by any stretch, just a quick and dirty indication of a hot wire.
It turns out that is all this is. It does not really try to indicate voltage beyond 12v vs 120v. There is a different indication for low voltage than line voltage but beyond that it is just a tick tracer. Not as cool as I hoped.
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