This circuit was obtained in a Popular Electronics of the 90s. The circuit uses integrated from the time, uncommon today. Note that the speaker has a higher impedance than ordinary speakers.
This circuit was obtained in a 90’s Popular Electronics. The frequency depends on C1, a component...
This short-range circuit can act as a wireless microphone. We got the schematic and the printed...
This sophisticated function generator circuit appeared in the September 1972 issue of Radio...