Re: Open garden gate indicator

[Nick Hull <nhull@xxxxxxx>]

In article <Vr5mi.234$fj5.120@trnddc08>,
 "Robert L Bass" <RobertLBass@xxxxxxxxxxx> wrote:

> > I am looking for something that will let me know
> > if one of my garden gates is open or closed.  I
> > saw something in the Home Automation catalog
> > but the magnetic switch doesn't look like it is
> > waterproof. I have also been thinking about
> > modifying a Craftsman Garage door open/closed
> > system that I use but am not quite sure how to
> > do that.  Any ideas out there?
>
> Virtually all of the magnetic sensors (called "contacts")
> used in the alarm industry are waterproof.  GE Security,
> GRI and Honeywell all make reliable, wide-gap contacts
> that could easily be used for this purpose.  Your choice
> will depend on the distance between the gate and the
> fence when it is closed.  If it's tight fitting (less than 1/2
> an inch) almost any standard door sensor will do. If the
> gap is larger, up to 3", you'll need one of the models
> used for a garage door.  Standard door contacts cost
> between $2 and $4 and wide gap; ones for a garage
> door cost about $11 or so up to $27, depending on the
> model.

I use magnetic reed switches on outdoor gates; they are
waterproof and work well BUT they can get welded by a near
lightning strike.  Proper protection (zeners, diodes, chokes)
make them last longer.  The high current ones take more abuse.