This circuit that generates signals between 1.5 and 2 kHz was found in a documentation from the 90's. The capacitor C1 can be changed to obtain other frequencies.
We found this circuit in a 1986 documentation. It causes 40 LEDs to flash sequentially. The big...
Exciting a sequential circuit with the output of a stereo we can make a set of lamps run at a...
This alarm from an old 1978 publication uses PNP transistors and driver and output transformers that are...