Undervoltage and overvoltage protection circuit for home appliances

Thread Starter

Dennis Soenarmin Tahar

Joined Mar 20, 2017
Dear mr,

Can you please assist us with the following:

To design a safety circuit that should provide for household
appliances for over-and undervoltage protection. The protective circuit must immediately switch off upon detection of low-and
high-voltage household appliance and upon detection of normal voltage switch on again after 3 minutes.

The protective circuit must comply with the following:

If the line voltage is within the normal range (100 to 130V ac), it will wait for the protective circuit 3 minutes before the output will
be energized. During these 3 minutes there is an amber LED light.

If the line voltage is outside the normal voltage, the output of the protective circuit will never be under tension.

If the line voltage is less than 100VAC, the protection circuit "low voltage" must indicate by a red LED that lights up. If the line
voltage is present, the protection circuit must pass a voltage greater than 105 Vac "normal tension" it will indicate by a green LED that
lights up.

Similarly, the line voltage protective circuit has to be higher than 130V ac "high voltage" will be indicated by a red LED that lights up.
Only when a voltage is less than 125VAC, it must indicate the protection circuit "normal tension" by a green LED that lights up.

Upon detection of over-and under voltage protection, the circuit should give a beep of 5 seconds. This should be constructed with an opamp oscillator circuit in this functionality.undervoltage and overvoltage schematic.JPG

The circuit does not work according the requirements.

Please check if there is there is something missing in the schematic or did i use some electronic components that will not work or maybe the values.

Best Regards,