Simple Mains Voltage monitor LM324
This Circuit helps in the monitoring of mains supply
voltage. It does not use a isolation step down transformer.
This has to be constructed only by skilled people with knowledge of
safety requirements.
C1 0.47uF can be brought down to 0.22uF for low LED currents, use high
efficiency ultra bright LEDs.C1 should be 440V AC or 630V DC plastic
axial yellow, polyester, polycarbonate, polypropylene, metalized
film.
R3-R6-R9-R14-R18 resistor divider determines the LED turn on or
threshold switch points, 10M for hysteresis.
Adjust
R16 preset with a log Plastic tweaker to get the led D2 to turn on when
input voltage is at 220V AC. This has to be done after PCB is put in a
sealed fire-retardant-plastic or epoxy box. drill a hole in box for
plastic tweaker.
LM324
- Low Power Quad Operational Amplifier
This Circuit is Not a Tested Design.
It is an Idea for study

Warning : This
Circuit is Mains Operated without
Isolation Transformer and will give lethal electric shock if touched
when the circuit is turned on. Test circuit only with DC 9V Bench Power
Supply to try it out. Do not use 230V AC.
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