This is the commercial circuit for the TRF-44 amplifier sold in Japan in the 1960s. The circuit provides a few hundred milliwatts and is intended to be used as small, battery-powered turntables.
We found this circuit in an Analog Devices documentation from the 90s. The circuit is based on a...
This circuit turns off a load after an interval of 8 to 80 seconds adjusted on the potentiometer. The...
Found elsewhere in this section, this circuit is from the April 1971 Radio Electronics magazine. Note...