Hello, I have a circuit below that uses Darlington pairs to increase the gain by a large amount. My guess is the high voltage oscillating devices Like (60 HZ) household devices and these devices produce a strong magnetic field and the antenna picks up these magnetic waves and since the gain is so sensitive, the base allows the magnetic waves to turn into a small current and actually to flow through the base and to the emitter, allowing for the current to flow from the collector to the emitter lighting the LED.
Is that the correct way of thinking of it? and the Website the i got the circuit from https://www.instructables.com/id/Non-Contact-Voltage-Detector-2/
and the site suggests 9v but I actually got the circuit to work with a coin cell battery.
Would using 9v allow for more range?
and what is the significance of the resistor values that they chose to use, with 5m ohms is used on the first collector of the transistor closest to the antenna and then the resistance valuse drops for each resistor going down the line?
Here is the circuit-----https://easyeda.com/editor#id=bb54f8e4a50d4775b5ca9899c618cd23