Designed for the audio track, this circuit was found in a Popular Electronics from the 90's. Other operational can be used and R7 can be 470 k. The frequency is 1 kHz.
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...