This circuit was obtained in an old European publication on FETs. The FET admits equivalent and the feed must have good filtration. Signal input cables and output cables must be shielded.
Obtained from an English publication, this circuit actually needs a current limiting resistor,...
This 2003 circuit serves to digitally show the intensity of a sound captured by a microphone....
Suggested by a Popular Electronics from the 90s, this circuit uses a buzzer to indicate the...