Found in an EDN from the 90s, this regulator makes use of the integrated circuit of the time. The input can be from 8 to 20 V.
This contact or reed switch actuation was found in a 1964 Electronic Design. The circuit can be...
This is the previous version, but with a simplification given by the use of the 7404 and 7408...
In the figure we present a circuit of a microphone signal conditioner using the SSM2167 integrated...