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.
The component used in this circuit is uncommon today, as the circuit was obtained from Motorola's Linear...
This circuit was found in General Electric documentation from the 1980s. The circuit is intended...
Taking advantage of the two stable states of a tunnel diode it is possible to build a switching circuit...