This circuit was found in a 1974 publication. It consists of a voltmeter for high voltages, up to more than 100 V, using a neon lamp.
With this circuit, from an old operational datasheet, it is possible to measure the CMRR,...
Found in a Popular Electronics from the 90s, this circuit can be adapted to use LEDs. The power...
The circuits shown in the figure, that of an infrared video signal transmitter and receiver, were...