Found in a 1966 documentation, this “coin finder” uses components from the era operating at 2.1 MHz. The circuit uses an audio amplifier for detection.
This circuit can control the power from 0 to 70% of the maximum power on a load. The circuit was...
This circuit from a June 1957 Radio Electgronics is for oscilloscopes of the time with a maximum...
This trigger uses two switching transistors that can still be found with some ease. The circuit is from...