Electric field indicator

I remember reading a constructional article, might have been 5 or 10 years ago, in an electronics magazine. From memory it used a single vacuum tube with a top cap grid connection, to maintain the lowest possibe leakage between the tube and the external field probe.

I've looked through all my back issues I have here with no luck. Anyone remember this or a similar article and could point me in the right direction. I want to build one !!

regards..

Why use a tube? A mosfet with the right characoristics is a much better fit.

What kind of electric field are you trying to measure? How accurate do you want to be? RF fields are easily measured with an antenna and amplifier but to measure DC electric field, you need some kind of capacitor and a chopper amplifier.

From memory, it was just intended to indicate the amount of static charge "in the air" eg might notice an approaching lightning storm etc. Just a novelty really.

regards..

An n-channel jugfet with an LED connected in series with it via a current limiting resistor. A 1M resistor is connected in series with the gate, when a negitive electric field is detected the LED will turn off.

Yes, thanks for pointing out the solid-state option !

regards..