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
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.
I use a window comparator and a timer for the 3 minute delay.
Please is there someone that could help me to calculate the resistors for the comparator?