This oscillator produces a modulated signal using a unijunction transistor. We found it in an American documentation from 1965. The circuit modulates in frequency the generated signal.
This circuit uses a Hall device from that time as a sensor. The circuit is from an English...
Found in Radio Electronics from the 90s, this siren finds many variations on this site. The...
This audio generator that produces both rectangular and sinusoidal signals was found in a...