This circuit was found in a Ferranti documentation from 1969. The transistors are common types of the company at the time. Smaller equivalents may be used. The output power is of the order of 150 mW.
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...