With the configuration shown in the figure, we have the relay being activated when the microphone picks up a sound and shutdown when the X1 reset sensor is activated.
This code switch was found in a 1990 Electronics Handbook. It can be mounted with BC558...
In this application we use an additional input circuit to enable the logic command with keys,...
This circuit was suggested by Signetics in 1980s documentation. The circuit makes use of the...