This is one of many possible touch switch configurations using CMOS integrated circuits. The circuit is from a 1980s American documentation. The power source must be isolated.
This circuit uses an impact sensor transistor called Pitran rare today. The circuit is from 1969...
Originally, this circuit was created to monitor the liquid level in the reservoir of a car's...
This Japanese commercial medium and short-wave radio uses 7 transistors and tunes the range from...