This crystal or galena radio was found in documentation from the 1990s. The earpiece must be a high impedance crystal or magnetic earpiece and D1 can be any germanium diode.
The frequency of the signal produced by this oscillator depends on the amount of light falling...
The circuit presented is based on a mechanical tuning fork. The circuit is suggested by National...
This is a well-known RC oscillator configuration using a 741 operational amplifier. The circuit is from...