Circuit Schematic AC Power Loss Alarm using LM555 and FET

Alarm. - Here is Circuit Schematic AC Power Loss Alarm using LM555 and FET. The circuit is powered by a 9v battery and is packaged in small plastic box with a 9v battery compartment.  A very popular opto-isolator is used to monitor the power line.  As long as there is AC power to the input, the n-channel FET Q1 is kept turned off.  As soon as power is lost, +9v is switched to the beeper circuit.  I used a CMOS version of the 555 timer to produce a 50ms pulse every 3 seconds.  The output of the timer drives an n-channel FET which in turn drives a very loud siren type beeper, available from Radio Shack.  The result is a sound maker which is very loud but only produces short chirps.  The sound is loud enough to be easily heard without drawing a lot of average current from the 9v battery.  Using the short 50ms pulses every 3 seconds, the average current when beeping is reduced to about 2 milliamps.  In standby mode the current is about 2 microamps.

Thank you for your coming here in Electronic Index blog, we hope the article above will help you to know more about your an electronic circuit schematic design and simulation and other. Please comment here when you want to share and other. Thank you.

Share on Google Plus
    Blogger Comment
    Facebook Comment


Post a Comment