Open door alarm?

Is there a device I can use or mutate such that if my front door is left open for more than a minute an alarm will sound - (people leave it looking shut but with a gap so loads of warm air is lost.) ((My front door is very heavy so I'm not sure a door closer would work in wind)) [g]
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george [dicegeorge] wrote:

A reed switch and a magnet would form the basis of the detection mechanism - especially as you can get made-for-purpose magnets and reeds.
Buzzers and 9V batteries are easy.
So that just leaves the problem of a time delay. I would use a 555 timer chip on a bit of veroboard, but if that scares you - I'm not sure what to suggest - maybe someone else can think of something?
--
Tim Watts

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On 12/11/2011 13:41, Tim Watts wrote:

A wall-wart power supply, and a "time-delay on" relay would do the trick to complete your circuit if the OP doesn't want to get down to component level.
SteveW
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On Sat, 12 Nov 2011 12:36:55 +0000, "george [dicegeorge]"

You want a fridge alarm - or similar. Try http://fridge-freezer-alarm.co.uk /
But I've never used them.
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On 12/11/2011 15:06, Simon Cee wrote:

This came up a few weeks ago. I have the one with the variable delay and it would do the job perfectly, but it's a bit bulky and wouldn't look very nice on a front door
--
Reentrant

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On 12 Nov,

Thermostat feeding electric bell (and wires to croc clips to apply to miscreants.....)
--
B Thumbs
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