This balance indicator for stereo amplifiers was found in an 80's Elektor. The components used are common. Zeners are 1.8 V or close to that value.
This 2004 circuit is based on the ionization effect that occurs in old incandescent lamps with...
This bidirectional current sensing circuit was found in a 2005 Linear Technology application manual....
This circuit can be used in decoration or to draw attention, in a “fake” assembly for example. What he...