"David Nebenzahl" wrote in message
.com...
On 2/7/2009 3:32 AM Terry Pinnell spake thus:

Can anyone point me towards a UK source (phone or online) for an
inexpensive cylindrical, enclosed reed switch, N/C, for use in a
burglar alarm circuit please.

I'm still googling but so far without success and want to place an
order for delivery Monday.

Sorry, I can't help, being in the US where things like this are trivially
easy to get.

Just one thing: did someone here say that switches like this were
typically N/O rather than N/C? And that such could be used for an alarm
circuit?

Think about it: if you have a N/O switch as an alarm sensor, all the bad
guy has to do to get in is to cut it out of the circuit. There's a reason
alarm switches are normally closed.

Hard to believe a N/C reed switch wouldn't be easy to buy somewhere in
England.


N/O reed switches are the simlest to build and in alarm systems are useually
held closed by a magnet on the other side of the door etc. so it will
activate the alarm if the door opens or the wire is cut.
But like you I find it hard to believe they are hard to get.

Terry, If you only need one I will post it from Australia if you are
desperate.

John G.