This circuit generates various types of sounds and can be used as a toy. The circuit is from Radio Electronics from January 1983. The amplifier can be replaced with a more modern type.
Found in English documentation, this touch sensitive switch must be powered by an isolation...
This circuit shows how to use a 3-terminal voltage regulator as a low frequency oscillator by...
The maximum input voltage of this circuit is 20V and the output current is 250 mA. The circuit is from...