This configuration is from the 70s, having been found in an American documentation. The transistors can be BC549 for Q1 and BC548 for Q2.
We found this circuit in the April 1975 Radio Electronics magazine. The circuit has a latch and...
We found this sophisticated home alarm in a 1994 documentation. The circuit supports sensors of...
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...