This traditional configuration found in a Radio Shack document can use 2N2646. More keys can be added, and the power can be supplied with voltages from 9 to 15 V.
This circuit was found in documentation from the 80s. It is based on unijunction transistors not...
This circuit was found in the May 1982 issue of Radio Electronics magazine. The circuit inverts the...
This alarm is designed for doors and windows, but nothing prevents it from being used in cars,...