This circuit was found in Delco documentation from 1965. The transistor is of the time, but any current power PNP with at least 500 mA collector current and 100 V collector voltage can be used.
Using 555 integrated circuits, this alarm circuit was found in a 90s American documentation. The signal...
Found in the May 1988 issue of Radio Electronics magazine, this circuit is sensitive to small...
We found this circuit in an English publication from the 1980s. The circuit uses current...