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.
This amplifier circuit applies its signal to an ordinary audio amplifier to pick up signals from a...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...
This oscillator generates a sinusoidal tone of 1750 Hz determined by the twin-T. The circuit can be...