AC Line Under/Over Voltage Alarm (March 29, 2009)

Published:2012/9/5 20:51:00 Author:Ecco | Keyword: AC Line , Under/Over Voltage, Alarm | From:SeekIC

Power lines, which deviate much beyond normal voltages can damage expensive electronic equipment. The circuit below sounds an alarm whenever the line voltage is higher or lower than normal. I set the alarm limits at about +-15% from standard levels. The circuit rectifies and filters the power line signal. I set the resistor values, so the DC voltage produced is close to 1% of the RMS value of the line. Thus, a 120vac line would yield about 1.2v DC. That voltage is fed to a pair of voltage comparators. Source: discovercircuits



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