ac grid sensor needed

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ac grid sensor needed

Post by max » Fri Nov 22, 2002 4:55 am

I need to build a small circuit to sense my 110 grid power. I want to know when the power goes out. The circuit should sense 110 ac and when no ac is present open another circuit dc (9vdc) and light up a bright led light and another circuit seperate to run dc to a pizzo buzzer to alert me so I can turn the buzzer off and still have a small amount of light to work with..Anyone who can help me with parts to get and small schematic would be appreciated. Lets keep it simple. Im a novice. thanks Max<p>[ November 22, 2002: Message edited by: Max ]</p>

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Re: ac grid sensor needed

Post by k7elp60 » Fri Nov 22, 2002 6:52 am

The simplest way I can think of is to connect a 120 Volt ac relay coil to the power line. Use the NC (normally closed )contacts as a switch wired is series with the 9V battery and the solid state buzzer. <p>As long as the relay has line power applied the contacts are open, like a switch in the off position. When the power goes off the contacts will close and turn on the buzzer.

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Re: ac grid sensor needed

Post by ampedtech » Fri Nov 22, 2002 7:50 am

Ned gives good advice.
my suggestion would to use a relay rated "continous duty" That means that the coil in the relay can be energized all the time. A relay not designed to be on all the time might (most likely will) burn out.

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Re: ac grid sensor needed

Post by MrAl » Fri Nov 22, 2002 1:09 pm

Hello,<p>Yes, some good ideas!<p>I'd like to add that perhaps a solid state
relay would work as well, or perhaps
a simple rectifier/resistor/NPN also.<p>Good luck with your circuits,
LEDs vs Bulbs, LEDs are winning.

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