This protection circuit for symmetrical 28 V power sources was found in a 1968 EEE documentation. The circuit can be adapted to use modern equivalent components.
This circuit appears in similar versions on this site. This is from a Popular Electronics from the 80's. The...
This two-transistor delay circuit from the 1960s was found in documentation from the time....
This circuit operates with signals from 150 kHz to 1 MHz and makes use of a known NAND CMOS gate....