Re: [OT] Pager for car alarm

[kimble <kim@xxxxxxxxxxxxxxxxxx>]

big_red_frog wrote:

> Something to make the car alarm trigger a pocket alarm so we know in
> the house if something is up.
>
> I have hunted on Maplin for pager etc, but can't find what I want.
>
> The alarm has a grounding output, so should be easy to intergrate.
>
> Anyone out there point me to something please?

I live in an area plagued by oversensitive car alarms, some with
identical sirens to mine, so I threw something together to do this using
a PIC and a Nokia data cable: PIC is connected to the siren line from
the alarm, and when that goes high, sends "ATDnnnnnn" at 2400
baud to my
old mobile (I'm lucky enough to have a SIM on the old OVP virgin tariff,
so no line rental).  I also provide power to the phone at 5V (which is
just enough to keep the battery charged) from the same regulator that
supplies the PIC, so the whole setup is nice and autonomous.

I've got it set to dial my mobile, which is set to divert to the house's
landline (and thereby triggers ungodly
deaf-alerting/sleeping-person-scaring stuff) when switched off at night.

Not the simplest solution, but I had the PIC stuff to hand, and it
didn't require modification of the phone.  I have a friend with a much
more elegant arrangement where a 12V relay connected across one of the
number keys of a much more ancient mobile triggers the speed-dial.

Of course the whole thing relies on having a mobile account with nothing
better to do, so as little line-rental as possible.  I don't know if
there are any PAYG tariffs that will go a decently long time between
top-ups these days.

This idea has the distinct advantage of as much range as you could
possibly need, and no extra pager unit to forget.


kim.
xxx