This signal injector and tracer (follower) was found in an old American documentation. The transistors can be general use and power is made with one or two common cells.
This circuit is from a 1957 Raytheon transistor manual. The diode can be of general-purpose...
This proximity switch or approach relay uses only transistors and directly controls a Triac. The...
The circuit presented here shows how two flip-flops of a 4027 can be connected to perform a...