This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply voltage. R1 can be reduced to lower trigger voltages.
This circuit was obtained in a 1975 documentation. It is intended for old vehicles that still use...
With this circuit it is possible to select transistors and their compliant test. Or circuit...
This power supply circuit with selectable voltages was found in the June 1979 issue of Radio...