This is a multi-part message in MIME format.

------=_NextPart_000_07D1_01C7B8AC.098EAEE0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

> Does someone know of a PIC chip circuit that will monitor the 220
> VAC mains and use them to run, but that can automatically switch to
> a battery power when the mains fails?  I need to make an alarm for
> when the power fails

Hi Miguel, you could use this to detect mains

http://home.clear.net.nz/pages/joecolquitt/txless/zc-detect-opto.gif

or something like the attached to switch

I agree with Bob about not making it too complicated but there
are a certain number of elements you'd need to have. A FET
would substitute for a relay, depends what power requirements
you need

The attached can potentially detect the mains in two ways. Vsense
is not strictly needed, but works. The diode after the 39k isolates
the reservoir cap to speed the switching

How my circuit (part of a clock) actually works is that the PIC s/w
looks for INT0 triggered by the mains. TMR0 is also running, and
times out if a mains cycle isn't received. The PIC releases the relay
and uses TMR0 as the back-up timing reference until mains is
restored

------=_NextPart_000_07D1_01C7B8AC.098EAEE0
Content-Type: image/gif;
	name="V-switch.gif"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
	filename="V-switch.gif"
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------=_NextPart_000_07D1_01C7B8AC.098EAEE0
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

------=_NextPart_000_07D1_01C7B8AC.098EAEE0--