This circuit oscillates in the fifth harmonic of the crystal frequency. The circuit is from a 90's documentation. L1 must be according to the desired frequency.
This small amplifier uses a loudspeaker as a microphone and can be used in a simple intercom. The...
September 2016 - It can be obtained by Mouser Electronics the new dual analog switches TS5A22364 /...
This different power control circuit with SCR was obtained from a 1967 magazine. The SCR can be...