Overvoltage Indicator (CB22007E)

Using a CA3130 operational amplifier, this circuit drives an LED when the voltage exceeds the value set in VR1.

CMOS 4001 Alarm with Latch (CB24374E)
We found this circuit in the April 1975 Radio Electronics magazine. The circuit has a latch and...
Alarm System (CB16793E)
We found this sophisticated home alarm in a 1994 documentation. The circuit supports sensors of...
Light Activated Alarm (CB26164E)
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...