This common circuit is from September 1984 Radio Electronics. The transistors are general purpose, and the frequency is given by the capacitors.
Found in Motorola documentation from the 90s, this circuit makes use of a triac from that time. The...
This transistorized signal injector was one of the first that we found using the well-known...
This 200-mW amplifier uses one of the first commercial power transistors. The circuit is from a...