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, which can only be used with incandescent lamps, is adapted to the common wall...
Audio frequencies in the 300 Hz to 30 kHz range can be measured with this circuit. Transistors allow...
In the event of a short in the output, the relay disarms interrupting the supply. To reset this...