Re: Re: Beam Breaks - worthwhile?

["Jon Payne" <jgpayne@xxxxxxx>]

I was thinking also that two may be needed for direction i.e. when you
enter
the lounge the light comes on, but not when you leave it...

jon
----- Original Message -----
From: "Paul Robinson" <ukcueman@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Thursday, August 14, 2003 3:56 PM
Subject: Re: [ukha_d] Re: Beam Breaks - worthwhile?


> Is a receive/transmit pair the only reliable way to do this?
>
> ISTR something that was both transmit and receive, relying on a
reflection
> to operate. Is there such a beast or did I imagine it?
>
> ----- Original Message -----
> From: <ian.bird@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Thursday, August 14, 2003 3:35 PM
> Subject: Re: [ukha_d] Re: Beam Breaks - worthwhile?
>
>
> >
> > Hi Shane
> >
> > I use beam breaks in a couple of door around the place with 100%
> > reliability. About now I should say I use them for switching
lights not
> > occupancy detection. If you plan to use the PIR system to do
lights you
> may
> > well be annoyed by the detection delay which means you have
already
walked
> > into something by the time the light comes on. Beam breaks solve
this
> > problem pretty much but are not always suitable depending on your
house
> > layout. Don't forget light level detection if you plan to go for
light
> > control. If it is daylight you may not want to turn on the lights
> depending
> > on other factors e.g. ambient light level. Here is some details
on this
> > project http://www.mollyology.com/MyHouseKitchenLights.htm
> >
> > I have used a very slightly modified version of the Maplin beam
breaks (
> > http://www.maplin.co.uk
product code MK120) and have mounted the IR LEDs
> > remotely from the PCB boards (cos they are big and ugly). I only
use
about
> > 6 feet of cable but you could probably mount them further away.
The
> > modification bit means they switch a reed relay rather than
sounding a
> > buzzer.
> >
> > Ian