Just curious - flashing LEDs on burglar alarms

[John]

These little flasher units look ok to begin with but after they run down its hard to find one where someone has actually bothered to get out a ladder and replaced the battery

[Alan]

I'd assume that they are to attract the attention of a possible thief in the dark that there is an alarm (working or otherwise) fitted?

[dennis]

Assuming you do do the calculations you discover that ~1AHr will last about a year (depending on duty cycle and brightness required). If you accept that you won't see a LED in bright daylight you could make it last longer by limiting the current even more. Or you could increase the current but shorten the flash (say 0.1 seconds every 10 seconds) to make it brighter. As you can get several AHrs in a battery then the claim could be true. Why do you think it isn't?

[Dave Plowman (News)]

Right.

[Dave Plowman (News)]

My thoughts too, given that a bell box fitted in an accessible place would be a bit of a giveaway...

[Dave Plowman (News)]

The whole point of an LED is it should be visible at all times, so this would require a super bright type with a reasonably fast duty cycle.

Of course if you used a low current type with a slow duty cycle it could last a year or so without going mad with the battery, but I'd ask what the point would be in doing so. ;-)

All the pro units I've seen have reasonably fast flashing bright LEDs. One that hadn't would be somewhat of a giveaway, IMHO.

[Andrew Gabriel]

Actually, with the advent of the EU ladder directive, the real ones now seem to be mounted about 8' high.

[graham]

In some systems, it also shows that there is a charge to the backup battery in the bell box.

No flashing light and you either have a fault in the bell box circuitry or the bell box battery is totally flat.

Graham

[Dave Plowman (News)]

Next door have just had one fitted. Within easy reach by standing on the front ground floor window sill. Which is wide and easy to get to.

Now in general I'm pleased about H&S regulations. But of course there are many safer ways of accessing 'heights' than a ladder.

[Dave Liquorice]

Wonderful, they'll be banning squirty foam next...

[dennis]

Squirty foam was for bell boxes. It doesn't work with electronic sounders.

[Lurch]

On Wed, 28 Sep 2005 23:15:03 +0100, "Dave Plowman (News)" scrawled:

But the problem is cost compared to neccessity. If I'm fitting an alarm the ladder is up for appx. half an hour and that is to fit the box, perform the tests and that's the lot done. There isn't another method that is so economically viable from a time to erect\initial outlay perspective.

[<me9]

It'll shut anything up! The sound won't pass through it, and it will fill the sounder and stop it moving.

[Matt]

If only Dr Dribble took heed :-)

[Dave Plowman (News)]

No - but a large hammer does. As with everything.

[Dave Plowman (News)]

I see where you're coming from, but a bell box which can be accessed by a yob from the streets easily *without* a decent sized ladder seems to me to be a nonsense.

[Lurch]

On Thu, 29 Sep 2005 22:24:07 +0100, "Dave Plowman (News)" scrawled:

Run that by me again?

[Jonathan]

I think I'll get the installer back to check it out. It's a brand new alarm fitted in a new house by the builder. Unfortunately it's a Honeywell Domonial so that rules out fiddling with it myself ...

... unless anyone here knows where to get the engineering software and how to make up a cable???

Some advice for the DIY types on this group: avoid this alarm -- turning it on and off is the extent of the DIY you can perform on it :(

[Dave Plowman (News)]

If there's any point in an external audible alarm in that it *may* discourage a potential burglar by its presence, it must be out of easy reach. That's all.

[Lurch]

On 30 Sep 2005 06:00:51 -0700, "Jonathan" scrawled:

There's a good reason for that.

Yes.

There's a good reason for that.

I'm looking into the flashing LED's thing, not sure if the Domonial has that feature tbh.