We found this circuit in American documentation from the 1980s. Transistors can be of general use. The frequency range of the generated signals ranges from 500 kHz to 10 MHz.
This proximity (capacitive) alarm triggers a relay that, in turn, triggers an audible warning...
This sensitive circuit was found in old documentation. The SCR can be any of the 106 series and...
This traditional multivibrator configuration uses an LDR as a sensor. The circuit emits sound when...