This circuit is from a publication from the 70s. The operational amplifier is from the period. Modern equivalents according to the motor current must be used.
This two-microphone amplifier was found in a April 1961 Radio Electronics Magazine. The circuit is...
We found this experimental musical instrument in a 1977 Radio Shack brochure. The sound produced...
With this circuit it is possible to modulate the radiation emitted by a laser diode in amplitude. The...