In the figure we have the configuration of series regulator protector suggested by Motorola in 1968 documentation. The transistors are of the time, being able to be used modern equivalents.
This circuit was found in documentation from the 1980s. The integrated circuit used is uncommon today...
This circuit activates a relay that has a lamp as a load. The circuit is from a Radio Electronics from...
This circuit was found in a 90s Popular Electronics. The circuit uses several relays in order to...