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 was found in documentation from the 1980s. The control pulses are obtained by an...
This high current regulator for TTL circuits was found in an old French documentation from the...
This circuit is an alternative to the previous circuit. We found it in the same article in the...