> A good car alarm should have its own reserve source of power, as many
> crooks will cut a battery cable to disable the alarm before tampering
> with the car.  This doesn't address the major limitation of car alarms:
> nobody cares (other than the car's owner) when the alarm goes off.

On the other hand, this may be a definite advantage of a DIY system; you
won't have to use that chip that sounds EXACTLY like every other single
car alarm on the planet (just about all of them sound like:

Dyeeeww dyeeeww dyeeeww dyeeeww
Braaaaaohwp braaaaohwp braaaaohwp braaaaohwp
Mehhhhp mehhhhp mehhhhp mehhhhp
Ooooo eeeee ooooo eeeee ooooo eeeee ooooo eeee

[actually, I think I got the sequence not quite right there, but for what-
ever reason all the car alarm vendors seem to use the same noisemaker chip.]