Found in a 1969 Electronics World, this circuit generates low frequency signals with two repetition bands. Transistors support modern equivalents.
The circuit, shown in the figure, consists of an audio oscillator that generates signals between...
This circuit was found in a 1992 PE Hobbyst. The circuit detects the presence of spy...
This circuit produces low power flashes in a LED. Frequency is adjusted by P1 and depends also on...