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 configuration makes use of currently uncommon components. In fact, we found it in...
This 1 kHz oscillator was found in the February 1970 issue of Radio Electronics magazine. It uses...
This circuit was found in Motorola documentation from 1968. Transistors can be modern equivalents, just...