Found in an 1989 R-E Experimenters Handbook, this circuit produces several sound effects that can be modified. The signal must be applied to an external amplifier.
This configuration from a 1976 technical documentation shows how to use a varicap in a direct...
This circuit was found in the October 1979 issue of Radio Electronics magazine. The circuit is...
When this alarm is off current drained is very low, only about 60 µA. The circuit can be powered...