This elaborate mixer is from an Electronics Today International from the 80s. Operational amplifiers are common and resistors with no value determine the gain of the amplification steps.
We found this circuit in the Radio Electronics magazine from November 1958. In the magazine it was...
This circuit was found in a 1990 English magazine. It is a system in which the audio signal from...
With a touch of a sensor, it is possible to turn on or off incandescent lamps. The circuit must...