Found in a 1967 EEE, this circuit uses the signal from the alternating current power grid to produce pulses from a Unijunction. The circuit is directly excited by the mains voltage.
Circuits like this one, using the LM386 audio amplifier, are available from other sources in this...
This bass and treble control only attenuates the corresponding signals, requiring further...
Using a large inductance, this circuit was found in a Popular Electronics from the 90s. The...