This transmitter emits a modulated signal at a frequency given by the first transistor in the phase shift oscillator. The circuit is from an Australian publication from 1991.
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...