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 low-pass filter with 741 op and symmetrical source was found in the August 1993 issue of...
We found this circuit in an old documentation. General purpose equivalent diodes can be used. The...
It can be obtained from Mouser Electronics, sensors (receivers) transmitters and benders for...