This power supply protection circuit using a relay was found in a 1967 documentation. The components are from the time, but current equivalents can be used depending on the power source current.
This is the circuit of a hearing aid amplifier manufactured by Sony in the 1960s. The circuit was...
Here we show a configuration in which we have a control voltage applied from a voltage divider, which...
This circuit was found in Motorola's 1968 documentation. The SCRs are then replaceable with...