On Wed, 15 Jul 2015 08:49:10 -0700, etpm wrote:

On Tue, 14 Jul 2015 19:45:41 -0500, Tim Wescott
wrote:

On Tue, 14 Jul 2015 16:12:49 -0700, etpm wrote:

I bought today a "hands free" garbage can for the kitchen. It said on
the box that it has a motion detector for hands free operation. The
unit as a whole is well made and has features I like. The problem is
that when slid under the counter the motion detector detects the
underside of the counter and the lid opens and stays open. So it must
detect reflected IR, whether moving or not. The under counter position
is where it must go. The hands free opening is why I bought it, it is
for use in the kitchen. All the electronics are in the top, which
comes off in order to remove the garbage receptacle. So I need some
sort of sheet IR absorber so that the thing will work properly under
the counter. I can operate it manually but I don't want to touch the
garbage can when I'm cooking and have food of one sort or another
stuck to my fingers. Anybody have any ideas? I thought about maybe
taking the thing apart and putting a mirror inside that would make the
sensor see at an angle so that it wouldn't detect the underside of the
countertop but then it might open when someone walks past. So it looks
like what I really is a good IR absorbing material that I can fasten
somehow to the countertop underside. Any suggestions?

Try black cardboard. Most things that look black in visible light look
black in IR, too (not everything, but most).

If it mostly works but still false-alarms, fold the cardboard into a
fan-
fold shape.

If that doesn't work, I'll give you a full refund of all charges for
writing this post.
Greetings Tim,
Mike suggested using a digital camera to look at the spot projected by
the garbage can. So I'm going to use the same camera to look at paper
and fabrics at the local crafts store. When I find something that looks
black to my IR sensitive camera I'll buy it.

Be sure to check how reflective it is when the light strikes it at an
oblique angle -- black and smooth can be dismayingly reflective, which is
why the insides of cameras are painted _flat_ black. Black and stair-
stepped can be less reflective than black and smooth.

Come to think of it, black felt may be best, if you're in a fabric store
anyway.

--
www.wescottdesign.com