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 is quite old, from 1964, but can still be mounted with BC558 transistors. The circuit is...
This configuration is very traditional, appearing in several publications around the world. This...
We found this circuit in an Electronic Engineering from the 90s. It applies to any logical family....