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 a General Electric documentation from the 1980s, this circuit makes use of a FET...
This circuit is based on an MC1408, an integrated circuit that is not common today. The...
Another way to increase the sensitivity of the circuit with the amplification of the sensor...