The circuit presented uses two common transistors and is powered by the circuit being tested. The circuit is for TTL logic, since its supply is 5 V.
This circuit was suggested by old French documentation, but it can be used as a shield, in which...
This battery charger was found in the Electronics Experimenter Special Projects of 1983. The...
This circuit is from the 80's but uses common components today. The relay is voltage sensitive...