This shield circuit is from an American documentation from 1969. The components can be modified according to the relay and power, and the coupler can be of a modern type.
This circuit for testing commercial NPN and PNP transistors was found in Radio Electronics...
The reference source for this circuit is a 1968’s Motorola publication. The circuit can be...
This circuit open and close the relay in intervals adjusted by the potentiometers. The capacitors...