Beep once when power fails. 12 volt relay is used as a switch. When power is available, relay pulls and capacitor charges via diode D1 and NO and Common contacts of relay. When power fails, relay turns off and capacitor discharges via Common and NC contacts and buzzer. Buzzer gives a short beep at that time. If more timing for beep is needed, connect one … Continue reading Simple Power Failure Alarm
It was a big problem in my house that, sometimes the Water heater left on for many hours after the use. It has a Thermostat to cut off but when the water cools, again it switches on. This causes hike in electricity bill. Finally I found a solution. Just connected a Timer based alarm with the heater AC socket so that it will also switches on when the heater turns on. After 30 minute, it gives a loud alarm to remind that the heater is On. Alarm continues for another 30 minutes or till the heater is switched off. So that alarm reminds to switch off the water heater. This can be used for Electric Iron also.