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.
With only one integrated circuit and few additional components, this amplifier has an output power...
For the 7 to 10 MHz band L1 is formed by 3 turns of 22 to 28 AWG wire in a ferrite core 15 to 20...
The circuit shown in the figure, activates a bar of 4 LEDs with an audio signal applied to its...