In article ,
wrote:
I want to fit alarm switches to a significant number of steel (Crittall)
windows but I'm concerned that the reed switch types will get confused
by the steel frame. Can anyone suggest alternatives?

I assume you mean the common surface mount types? The flush ones I used
would be a problem with steel windows.

But the answer would be try one and see. Just connect your DVM across the
reed switch. Perhaps glue a small piece of wood to the frame and the
sensor to that.

--
*On the seventh day He brewed beer *

Dave Plowman London SW
To e-mail, change noise into sound.