Occupancy sensor

[Mike Barnes]

I've just fitted a new LED ceiling light with a built-in occupancy sensor.

It works well, actually rather too well, because I can't seem to reduce its sensitivity. I want to mask the sensor from a particular direction. I started off by covering part of the white dome projecting from the middle of the control box, which I guessed was the sensor, with black insulation tape. No effect. After various other failed attempts I'm masking more and more of the entire control box with a double layer of aluminium foil. What I find is that the sensitivity is almost unaffected until I increase the percentage masked to about 90% at which point the light decides to refuse to turn off.

All this is unaffected by the presence or absence of the diffuser. And yes, I have turned the sensitivity down to minimum.

I've just noticed that the item description says "RF sensor" so I think I might just be wasting my time.

Any ideas?

[Bill]

In message , Mike Barnes writes

Tin foil may work, it would certainly help to screen it in one direction, my main reservation would be that it may confuse the heck out of the sensor by reflecting too much signal back into it.

As I typed the above a 2nd thought came to mind, do you have any RF absorbent foam? That would cut and shape easily and not reflect back at the sensor so much as foil. I can't offhand think of a simple source, but you could always try putting bits of likely black foam in the microwave to see if it gets hot, if it does try a bit!

Have fun........

[pamela]

What a great product.

I tried some LED sensor bulbs with a PIR sensor rather than your RF sensor. These were for use in corridors at home but they're not sensitive enough because you have to be quite close before they switch on. I got some bulbs like this:

[Mike Barnes]

Interesting thought. I can get conductive foam designed for packing semiconductors very cheaply on eBay (though it rankles when I've thrown away so much in the past). The main thing that's putting me off is the likely shadows. But I'll give it a go.

[Brian Gaff]

I think you are correct. Most of these nowadays do not use motion sensors as otherwise sleeping people would suddenly be in the dark. Myself, I'd be very interested in how it could be done. Surely a still person would be very hard to detect. I know at one London Radio station the lights in the studio have occupancy sensing and every ten minutes or so the presenter has to get up and wave his or her hands about like a demented chimp to keep the lights on. Brian

[Brian Gaff]

Suppliers of anachoic chambers to companies making radar systems can have this stuff, and often can have small ofcuts where they have fitted some. However quite how you would get this need to the right people without a paper trail as long as the The Thames, I'm not so sure! I got some once from that test gear company which starts with Rh. Brian

[ARW]

So you know Chris Evans then?

[Mr Pounder Esquire]

It's a very large building full of dark passages and is a maze. Open a door, walk in and a light goes on, 60 seconds later it goes off and you are in the pitch black. Bloody wonderful when you are on your knees.