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 from the 1980s, this circuit can use any germanium diode. The...
This configuration, which requires a symmetrical power supply for the 741, can be implemented with other...
This 3-digit code switch was obtained from an old American documentation. The capacitor is 470 uF...