This circuit was originally intended for reading movie soundtracks. The circuit is from 1967 and was found in an English publication. The sensor is semiconductor type.
This circuit produces the sound of percussion such as blocks, drum, bell, etc. The frequency...
We found this oscillator in a publication from the 1960s. The frequency is around 600 Hz with the...
Found in a Popular Electronics from 1992, this circuit uses a PLL567 in an audio meter bridge that...