This circuit is from a 1968 publication. Here we have several types of resistive sensors with individual adjustments triggering a single SCR. Power depends on the type of sound device to be triggered.
In applications where there is no danger of any contact with live points in the circuit by the...
This circuit was found in the May 1989 issue of Radio Electronics magazine. The components can be...
The frequency of this oscillator is given by the coil and by C1/C2. The circuit supports any...