On Jan 4, 5:17*pm, jigo wrote:
Do those self-installed door alarms that are supposed to emit an alarm
work? *The casing around the doors in my house, and I think most
houses, is curved (i.e., it's not flat like the door). *Doesn't the
part of the alarm placed on the door have to form a magnetic
connection to the piece on the casing so the alarm goes off when they
come apart? *I don't see how I could get them to match up if the
casing part is curved; they'll meet at an angle.

Another concern I saw on Amazon was that the alarm (a GE) did not go
off if the door was opened too quickly. But that's what a burglar is
likely to do. They just kicked in the door (which had a deadbolt lock)
of my neighbor's house.

I'm sure it depends on the specific model/design of the switch.

It may not matter that the two elements meet at an angle. But
probably
will look uglier in that case. You could presumably get it to mount
straight by using a small wedge of wood between it and
the doorframe. Or you could cut out a small piece of the frame trim
to fit around the sensor.

If the switch works by detecting that the other part is resting next
to it,
then it shouldn't matter how quickly the door is opened. If it works
by
detecting a magnetic field generated by one part passing the other,
then
there might be a problem.

The house I grew up in had a closet with a light that was controlled
by
a spring-loaded brass rod built into the hinge side of the door frame.
Open the door, the rod extended slightly and the light came on.
Elegant design, almost invisible, and even when spotted still
aesthetically
pleasing, and very reliable.