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.
In the figure we have a configuration that allows to test NPN transistors and with the addition of a...
Pressing S1 the LED glows by a time interval depending on the capacitor. Time intervals in the...
The oscillator of this circuit operates around 8 MHz, but the output will be at a frequency three times...