A cheap and noisy "loop" alarm

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A cheap and noisy "loop" alarm

Postby psychobilly » Thu Jul 24, 2008 6:50 pm

Loop alarms are like the ones used in shops to stop you walking away with the items on show... well make a load of noise if you try.

B&Q do a Friedland shed alarm kit for £10.98 which gives 15s exit and entry delay before the alarm sounds - I use one on the observatory.

The 15s delay is a bit long for a loop alarm so a bit of scoping around the circuit shows that by adding a 680k resistor across R3 and R7 you now have delays of no more than a second or so, I replaced the door contacts with a loop made from a 3.5mm mono extension lead - cut the lead in half, shorted both conductors of each half together and soldered them to the "contacts" pads on the PCB.

The very loud sounder was mounted to the top of the case witht he wiring being shortened and soldered to the "siren" pads on the pcb...

The loop can be extended by adding additional 3.5mm extension leads to the "circuit".

When im setting up outside and and walking back and fore to the house I can now easily "protect" the kit in the observatory by "looping" it all together with the Alarm [:D]

Would be ideal for scopes/tripods etc left outside while you pop in for a cuppa...

[image]http://www.btinternet.com/~psmithuk/stuff/scopealarm.jpg[/image]

Billy..



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RE: A cheap and noisy "loop" alarm

Postby bajr » Thu Jul 24, 2008 9:53 pm

Here's my woof alarm.Emits an ear splitting bark no batteries required.
-Hefty bills when i take him for a service though[&:]

Brian

[image]local://2794/1A4545CBB31A44B5B4494931BA49BB22.jpg[/image]
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RE: A cheap and noisy "loop" alarm

Postby brianb » Thu Jul 24, 2008 10:10 pm

Yes but does he sleep?

I always thought those bits of kit were high maintainance - need feeding, cleaning up after, taken walkies, expensive running repairs, sweet talking neighbours whose moggies have been torn to bits ....
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RE: A cheap and noisy "loop" alarm

Postby bajr » Thu Jul 24, 2008 10:10 pm

[quote]I always thought those bits of kit were high maintainance - need feeding, cleaning up after, taken walkies, expensive running repairs, sweet talking neighbours whose moggies have been torn to bits .... [/quote]


You talking about Eric or my children Brian?[;)]

Brian
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RE: A cheap and noisy "loop" alarm

Postby brianb » Thu Jul 24, 2008 11:00 pm

Eric.

Kiddies get running repairs done on the National Health Service.

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RE: A cheap and noisy "loop" alarm

Postby bajr » Fri Jul 25, 2008 9:30 pm

[quote]Kiddies get running repairs done on the National Health Service. [/quote]

Thank crunchie! If carlsberg done health services it would be like Britains[:)]

Brian
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RE: A cheap and noisy "loop" alarm

Postby psychobilly » Fri Jul 25, 2008 9:46 pm

[quote]ORIGINAL: bajr


Thank crunchie! If carlsberg done health services it would be like Britains[:)]

Brian
[/quote]

What stale and insipid.....

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RE: A cheap and noisy "loop" alarm

Postby bajr » Fri Jul 25, 2008 9:46 pm

[quote]PsychoBilly
quote:

ORIGINAL: bajr


Thank crunchie! If carlsberg done health services it would be like Britains

Brian


What stale and insipid..... [/quote]

Maybe a little frayed round the edges, but i beleive the best doctors and nurses anywhere in the world.

Brian
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RE: A cheap and noisy "loop" alarm

Postby psychobilly » Fri Jul 25, 2008 9:46 pm

yeah we bring them in form overseas...depriving their home countries of homegrown talent...a consequence of the global village perhaps


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