This noise limiter for low intensity signals was found in a 73 magazine for radio amateurs from the 90's. The circuit is for signals from 10 mV to 1 V amplitude.
This Kirlian machine circuit uses a car ignition coil. The circuit is from a Radio Electronics from May...
This circuit works both as a preamplifier and activates a relay when speaking in front of the...
This phase inverter with transistors, used in audio amplifiers, was found in a French publication from...