Found in Ferranti's 1968 documentation, this circuit uses a Darlington photo transistor to drive a 12V relay. The circuit can be implemented with modern equivalent components.
This circuit is from an old manual, but can be easily assembled as the integrated one is still...
The simple transistor test shown in the figure can be powered by a 9V battery. The test is for...
This regulator can use BD'136 as the main transistor and as a reference next to a BC548 zener. The...