With this circuit you can produce the sound effect passing from one channel to another. The circuit is from Mullard documentation from the 1960s. The transistors may be the BC548.
This circuit uses unusual operational amplifiers, but equivalents can be tried. FETs can also be...
This circuit was obtained in a 1991 publication. What it does is to amplify a signal with unit...
This small digital transmitter uses a 1 MHz crystal, or another nearby frequency, to produce a...