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?
Thanks,
Eric

On 7/14/2015 7:12 PM, wrote:
... 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. ...

How about putting the mirror under the counter top?

On Tuesday, July 14, 2015 at 7:51:32 PM UTC-4, Bob Engelhardt wrote:
On 7/14/2015 7:12 PM, wrote:
... 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. ...

How about putting the mirror under the counter top?


I would try some aluminum foil taped under the counter top.

If you really need an adsorber, you could try some black paint. I would try black paint on cardboard before painting the underside of the counter.

How about a make and model? The manufacturer might have some info that would help figure out a solution.

Dan

On 7/14/2015 4:12 PM, 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?
Thanks,
Eric

Get out your digital camera and take a look to see where the light
comes out and the pattern on the underside of the counter.
You may be able to mask the light source.
You can use the camera to look at reflectivity of various surfaces.
The TV remote makes a usable source of infrared.

The camera is not very sensitive in the infrared, but often good
enough to do the job.

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.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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

Isn't it good enough looking to be left out while you cook?

--
The business of America is not business. Neither is it war. The business
of America is justice and securing the blessings of liberty.
-- George F. Will

On Tuesday, July 14, 2015 at 4:07:23 PM UTC-7, wrote:
I bought today a "hands free" garbage can for the kitchen. .... 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.

Two solutions: redirect (use a mirror or prism) the line-of-sight of the sensor
so it sees cockeyed. Or, use a circular polarizer sheet (like old CRT
monitors were sometimes equipped with, to keep contrast high).

Easiest way to do the prism thing, is to get one of those whole-page Fresnel
lenses, and snip a few inches off the edge. You can experiment a bit to
see if it works before you damage your dollar-store magnifier.

Don's got it - IR is what you feel as heat. Heat rays. metal might
reflect it unless it were etched and ready to absorb. I'd try
the black paint and the cardboard idea is spot on. If it doesn't work
then apply another material. A rug would be good, but grabs dirt.
Martin

On 7/14/2015 7:19 PM, wrote:
On Tuesday, July 14, 2015 at 7:51:32 PM UTC-4, Bob Engelhardt wrote:
On 7/14/2015 7:12 PM, wrote:
... 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. ...

How about putting the mirror under the counter top?


I would try some aluminum foil taped under the counter top.

If you really need an adsorber, you could try some black paint. I would try black paint on cardboard before painting the underside of the counter.

How about a make and model? The manufacturer might have some info that would help figure out a solution.

Dan

Martin Eastburn fired this volley in
news
A rug would be good, but grabs dirt.


....not as likely to, upside-down over the top of the thing.

But any _really_flat_black surface ought to work. "Just black paint"
might not... even some of the 'flats' are kind of glossy. But something
sooty black will likely work quite well... unless it ends up heating to
the point of re-radiating that IR!

In that case, a heat-conductive underlayment is called for, to move the
warmth away from the hot-spot. I'd be tempted to try a heavily-sooted
sheet of aluminum. It'll never be touched up there.

Black velvet might work, too.

Lloyd

Black felt cloth or maybe a black towel. Black to absorb, rough to scatter
what does reflect.
-----
Regards,
Carl Ijames
wrote in message ...

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?
Thanks,
Eric

I was just looking at some of my IR photos, and realized asphalt comes
up dead black, near zero reflectance. Maybe give a clue to materials
that absorb. Suspect maybe rubber might absorb too. Maybe a patch of
innertube stapled to the underside of the counter?

Jon

On Tue, 14 Jul 2015 17:19:12 -0700 (PDT), "
wrote:

On Tuesday, July 14, 2015 at 7:51:32 PM UTC-4, Bob Engelhardt wrote:
On 7/14/2015 7:12 PM, wrote:
... 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. ...

How about putting the mirror under the counter top?


I would try some aluminum foil taped under the counter top.

If you really need an adsorber, you could try some black paint. I would try black paint on cardboard before painting the underside of the counter.

How about a make and model? The manufacturer might have some info that would help figure out a solution.

Dan
Greetings Dan and Bob,
I thought of this and tried the aluminum foil thing last night when I
got home and could only make it work when it was angled nearly 45
degrees and I'm looking for a flat solution. Thanks for the
suggestions though.
Eric

On Tue, 14 Jul 2015 17:26:31 -0700, mike wrote:

On 7/14/2015 4:12 PM, 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?
Thanks,
Eric

Get out your digital camera and take a look to see where the light
comes out and the pattern on the underside of the counter.
You may be able to mask the light source.
You can use the camera to look at reflectivity of various surfaces.
The TV remote makes a usable source of infrared.

The camera is not very sensitive in the infrared, but often good
enough to do the job.
That's a great idea Mike. I have a digital camera I modified to see
only NIR so it should great. Then I can maybe use black paper like Dan
suggested.
Eric

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.
Cheers,
Eric

On Tue, 14 Jul 2015 18:54:32 -0700, Larry Jaques
wrote:

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

Isn't it good enough looking to be left out while you cook?
The garbage can is always out in the open on three sides. At one end
of the counter the countertop extends past the cupboard and this is
where the garbage can goes. Out of the way but very accessible.
Eric

On Wed, 15 Jul 2015 17:40:21 +1000, Jon Anderson
wrote:

I was just looking at some of my IR photos, and realized asphalt comes
up dead black, near zero reflectance. Maybe give a clue to materials
that absorb. Suspect maybe rubber might absorb too. Maybe a patch of
innertube stapled to the underside of the counter?

Jon
If I can't find some paper or fabric to work I do have some rubber
sheet I copuld try. Thanks.

On Tue, 14 Jul 2015 16:12:49 -0700, 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?
Thanks,
Eric

About the only thing that WILL work is a mirror, unfortunately. You
might..might try some black terry cloth type material above the sensor
under the counter..but its gonna be iffy if it works.

Gunner, who installed thousands of infrared security sensors when he
ran an alarm co.

On Wed, 15 Jul 2015 11:41:18 -0700, Gunner Asch
wrote:

On Tue, 14 Jul 2015 16:12:49 -0700, 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?
Thanks,
Eric

About the only thing that WILL work is a mirror, unfortunately. You
might..might try some black terry cloth type material above the sensor
under the counter..but its gonna be iffy if it works.

Gunner, who installed thousands of infrared security sensors when he
ran an alarm co.

I am somewhat curious as to how the viewing area of the IR sensor is
laid out.

You may wish to review this article

https://learn.adafruit.com/pir-passi.../how-pirs-work

Im assuming you have one of these...

https://www.google.com/search?q=ir+g...utf-8&oe=utf-8

Im wondering ...is the sensor pattern angled upwards to avoid
triggering by the passage of dogs and cats? Will the sensor simply
allow you to turn it upside down and sense low angle movement, rather
than high angle movement?

Can it be shimmed in its mounting to look at a lower angle?

Gunner

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 4.170...
Martin Eastburn fired this volley in
news
A rug would be good, but grabs dirt.


...not as likely to, upside-down over the top of the thing.

But any _really_flat_black surface ought to work. "Just black paint"
might not... even some of the 'flats' are kind of glossy. But something
sooty black will likely work quite well... unless it ends up heating to
the point of re-radiating that IR!

In that case, a heat-conductive underlayment is called for, to move the
warmth away from the hot-spot. I'd be tempted to try a heavily-sooted
sheet of aluminum. It'll never be touched up there.

Black velvet might work, too.

And if it doesn't you can always just drink it. Then you won't care.

On 7/15/2015 8:45 AM, wrote:
On Tue, 14 Jul 2015 17:26:31 -0700, mike wrote:

On 7/14/2015 4:12 PM, 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?
Thanks,
Eric

Get out your digital camera and take a look to see where the light
comes out and the pattern on the underside of the counter.
You may be able to mask the light source.
You can use the camera to look at reflectivity of various surfaces.
The TV remote makes a usable source of infrared.

The camera is not very sensitive in the infrared, but often good
enough to do the job.
That's a great idea Mike. I have a digital camera I modified to see
only NIR so it should great. Then I can maybe use black paper like Dan
suggested.
Eric

I still think you're attacking the wrong end of the problem.
If you can mask or reflect right at the source, you won't need
any absorber.
I have a motion detector light that was always triggering when I
didn't want.
I put some black tape along the side of the emitter to restrict the
angle (field of view). Worked great.

I'm still confused about why it matters what reflects as long as it isn't
moving.
Typical PIR projects multiple images onto the sensor.
It triggers when there's amplitude modulation produced by changing
patterns as something moves in range.

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

In article ,
wrote:

On Wed, 15 Jul 2015 17:40:21 +1000, Jon Anderson
wrote:

I was just looking at some of my IR photos, and realized asphalt comes
up dead black, near zero reflectance. Maybe give a clue to materials
that absorb. Suspect maybe rubber might absorb too. Maybe a patch of
innertube stapled to the underside of the counter?

Jon
If I can't find some paper or fabric to work I do have some rubber
sheet I copuld try. Thanks.

The blackest common paint is Krylon 1602 Ultra Flat Black, beloved in
optics circles everywhere.

..http://www.amazon.com/Ultra-Flat-Bla...t/dp/B0064OW9D
W

Joe Gwinn

On Wed, 15 Jul 2015 08:51:51 -0700, wrote:

On Tue, 14 Jul 2015 18:54:32 -0700, Larry Jaques
wrote:

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

Isn't it good enough looking to be left out while you cook?
The garbage can is always out in the open on three sides. At one end
of the counter the countertop extends past the cupboard and this is
where the garbage can goes. Out of the way but very accessible.

OK. How about screwing a Z shaped paddle onto the lid by the sensor?
Construct of sheetmetal and coat with spray-on auto undercoating, with
4-6" for your hand to swipe the sensor. Or just undercoat the
underside of the offending cabinet?

--
The business of America is not business. Neither is it war. The business
of America is justice and securing the blessings of liberty.
-- George F. Will

On Tuesday, July 14, 2015 at 7:07:23 PM UTC-4, 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?
Thanks,
Eric

Black electrical tape works very well at blocking all the
light from (Si) photodiodes. I don't know how much
is absorbed vs reflected. But it's easy to try.

George H.

On Wed, 15 Jul 2015 13:11:27 -0700, mike wrote:

On 7/15/2015 8:45 AM, wrote:
On Tue, 14 Jul 2015 17:26:31 -0700, mike wrote:

On 7/14/2015 4:12 PM, 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?
Thanks,
Eric

Get out your digital camera and take a look to see where the light
comes out and the pattern on the underside of the counter.
You may be able to mask the light source.
You can use the camera to look at reflectivity of various surfaces.
The TV remote makes a usable source of infrared.

The camera is not very sensitive in the infrared, but often good
enough to do the job.
That's a great idea Mike. I have a digital camera I modified to see
only NIR so it should great. Then I can maybe use black paper like Dan
suggested.
Eric

I still think you're attacking the wrong end of the problem.
If you can mask or reflect right at the source, you won't need
any absorber.
I have a motion detector light that was always triggering when I
didn't want.
I put some black tape along the side of the emitter to restrict the
angle (field of view). Worked great.

I'm still confused about why it matters what reflects as long as it isn't
moving.
Typical PIR projects multiple images onto the sensor.
It triggers when there's amplitude modulation produced by changing
patterns as something moves in range.
Even though the thing says it is motion activated I think it just
detects its own reflected light because when the garbage can is slid
under the counter the lid opens and stays open. No motion required. So
I think it does not have a PIR detector but instead sends out pulsed
IR and when it is reflected back the lid opens. Just holding my hand
over it will cause the lid to open and stay open.
Eric

On Wed, 15 Jul 2015 15:47:46 -0500, Tim Wescott
wrote:

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.
That's what I'm thinking. Black felt opr black construction paper. My
camera should be able to tell me how reflective something is.
Eric

On Wed, 15 Jul 2015 21:53:42 -0400, Joe Gwinn
wrote:

In article ,
wrote:

On Wed, 15 Jul 2015 17:40:21 +1000, Jon Anderson
wrote:

I was just looking at some of my IR photos, and realized asphalt comes
up dead black, near zero reflectance. Maybe give a clue to materials
that absorb. Suspect maybe rubber might absorb too. Maybe a patch of
innertube stapled to the underside of the counter?

Jon
If I can't find some paper or fabric to work I do have some rubber
sheet I copuld try. Thanks.

The blackest common paint is Krylon 1602 Ultra Flat Black, beloved in
optics circles everywhere.

.http://www.amazon.com/Ultra-Flat-Bla...t/dp/B0064OW9D
W

Joe Gwinn
Thanks for that Joe. I am going to need some flat black paint to paint
the inside of some optics assemblies in the not too distant future.
Eric

On Wednesday, July 15, 2015 at 4:02:09 PM UTC-4, Bob La Londe wrote:
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 4.170...
Martin Eastburn fired this volley in
news
A rug would be good, but grabs dirt.

...not as likely to, upside-down over the top of the thing.

But any _really_flat_black surface ought to work. "Just black paint"
might not... even some of the 'flats' are kind of glossy. But something
sooty black will likely work quite well... unless it ends up heating to
the point of re-radiating that IR!

In that case, a heat-conductive underlayment is called for, to move the
warmth away from the hot-spot. I'd be tempted to try a heavily-sooted
sheet of aluminum. It'll never be touched up there.

Black velvet might work, too.

And if it doesn't you can always just drink it. Then you won't
care.

Drink Black Velvet? There are plenty of recipes for Black Velvet Cake.

On Wed, 15 Jul 2015 08:53:19 -0700, wrote:
On Wed, 15 Jul 2015 17:40:21 +1000, Jon Anderson
wrote:

I was just looking at some of my IR photos, and realized asphalt comes
up dead black, near zero reflectance. Maybe give a clue to materials
that absorb. Suspect maybe rubber might absorb too. Maybe a patch of
innertube stapled to the underside of the counter?

Jon
If I can't find some paper or fabric to work I do have some rubber
sheet I copuld try. Thanks.

Eric,

It has been a few years since I dealt with IR, and that was near IR (e.g.
your typical remote control):

https://en.wikipedia.org/wiki/Infrar...n_the_infrared

I was attempting to make a small robot's IR reflectance sensors work so
it would follow a black line, but a number of visible-light "black"
substances did not have any effect (the sensor couldn't distinguish them
from plain white):

- InkJet black ink (water-based)
- Permanent markers (those tested)
- Black acrylic paint
- At least one marker claiming to be "pigmented"

These _were_ noticed:

- Laser printer "black" (fused plastic toner)
- Black tempera paint
- Strips of black supermarket-chicken containers (both the foamy kind
and the flat plastic kind)

I was _told_ that most "pigmented" paints, markers would absorb IR (at
least near IR), but my own results were mixed -- possibly a tribute to
American Marketing's triumph over providing clear information. ( Sigh. )

Just for grins, if you have access to a laser printer, try printing a
solid black square of "sufficient size" and hold/tape it in place to see
if it helps.

Good luck...


Frank McKenney
--
A beginning naturalist, fired by adolescent enthusiasm but short
theory and vision, I had schooled myself in natural history with
field guides carried in a satchel during solitary excursions into
the woodlands and along the freshwater streams of my native state.
I saw science, by which I meant (and in my heart I still mean) the
study of ants, frogs, and snakes, as a wonderful way to stay
outdoors. -- Edward O. Wilson, "Consilience"
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com

Is that Friction tape - a.k.a. tar tape or the electrical tape ?
Martin

On 7/16/2015 8:55 AM, wrote:
On Tuesday, July 14, 2015 at 7:07:23 PM UTC-4, 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?
Thanks,
Eric

Black electrical tape works very well at blocking all the
light from (Si) photodiodes. I don't know how much
is absorbed vs reflected. But it's easy to try.

George H.

On 2015-07-15, wrote:
On Tuesday, July 14, 2015 at 7:51:32 PM UTC-4, Bob Engelhardt wrote:
On 7/14/2015 7:12 PM, wrote:
... 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. ...

How about putting the mirror under the counter top?


I would try some aluminum foil taped under the counter top.

Not likely any good.

If you really need an adsorber, you could try some black paint. I
would try black paint on cardboard before painting the underside of the
counter.

You want flat black, not shiny.

And start out with some thing like a sheet of black velvet which
should be a pretty good absorber.

Good Luck,
DoN.

--
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