With this circuit you can produce the sound effect passing from one channel to another. The circuit is from Mullard documentation from the 1960s. The transistors may be the BC548.
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...