This variable frequency circuit was found in a Popular Electronics from the 90s. The circuit outputs to a small speaker and can be powered by voltages as low as 3 V.
This beat frequency oscillator or BFO was found in an American 1980s documentation. The circuit is...
We found this setting in the Texas Instruments opto-electronics manual. The bipolar can be the...
This bistable control uses a 4069 as bistable. The circuit can drive relays up to 100 mA with the...