Found in American documentation from the 1980s, this circuit makes use of components of the time, which are uncommon today. The circuit detects the approach using a sensor formed by metal plates.
Found in a 1964 Electronic Design, this circuit shows how to modulate a signal with a dynamic low...
This circuit was found in a 1971s English magazine. We can still assemble it using BC548...
This circuit was obtained in a Popular Electronics of the 90s. The circuit uses integrated from...