Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

In article ,
D Yuniskis wrote:
Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

The trick is to make up your own fittings and put the ballasts elsewhere.
Then all the moulding has to cover is the tube itself. Which is not going
to be any larger in practice than anything which conceals the light source
- unless you're going to fit downlighters into the cupboard bottom which
would cause other problems. ;-)

--
*Atheism is a non-prophet organization.

Dave Plowman London SW
To e-mail, change noise into sound.

D Yuniskis wrote in message
...
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!


The largest component in a "laptop" inverter is the transformer, with the SM
stuff then about double that in volume total. Could you not have the
inverter almost ingeral to the lamp and run 12 to 20V supplies to each lamp,
of course if you want dimming then some extra wiring + control


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"D Yuniskis" wrote in message
...
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

LED 'tubes' for under-cabinet illumination, already exist, I believe. Seem
to think that I've seen them in Ikea. Go take a look at their website

Arfa

I like the idea of recycling notebook backlights, rather than tossing them.

Building one from scratch is going to be pricey, because white LEDs have not
gotten really cheap. And all the ones I've seen have a bluish tinge which
might be disconcerting in the kitchen.

GE used to make "stick-up" fluorescents, which could be attached with screws
or double-sided tape. I don't think they're made anymore, but you might
look.

In article , D Yuniskis wrote:
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

I used some led's and put the sink side inside a little circular
plastic dish. It actually some kind of laboratory specimin container.
Its not perfect as I had to put some black tape around it so
you don't see the light. I am using a moderate level of light, and they are
always on. I intend on hooking them up to battery backup,
along with the under counter bathroom lights I installed.
With the Cree warm lights, i get plenty of brightness using only 50 ma.
I had to use 100 ma. with some Luxeons. I am only using one lamp per couple feet of
coverage. I also instaled an over the counter one in the bathroom, which
lights up the ceiling.

greg

N_Cook wrote:
D Yuniskis wrote in message
...

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The largest component in a "laptop" inverter is the transformer, with the SM
stuff then about double that in volume total. Could you not have the
inverter almost ingeral to the lamp and run 12 to 20V supplies to each lamp,
of course if you want dimming then some extra wiring + control

If you colocate the inverter with the CCFL "panel", then it will
either have to be located *above* (i.e., behind) the panel *or*
it will interrupt the light path from the tubes across the panel
itself (you'd have to see how these diffusers are built to understand
how that would result in a "shadow" cast normal to the panel).

Locating them above/behind the panel makes the panel thick,
again. The available space under the cabinets is approx
3/4". And, the less you use, the more concealed the light
source will be.

If you have to move the inverters, then you run into Code issues
as 600V requires special treatment (even though it is very low
current). And, you then have to come up with a place to hide
*several* inverters -- and DC supplies -- to power each of the
panels.

frown No, not a practical approach. But, amusing to consider!
(I have a ready supply of "defective" LCD monitors)

A friend, in jest, suggested *not* removing the active displays
from the displays but, instead, piping live video through them
and installing stainless steel (or other highly reflective
countertops) so you could watch videos *in* your countertops...

X-/

Arfa Daily wrote:
"D Yuniskis" wrote in message
...

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

LED 'tubes' for under-cabinet illumination, already exist, I believe. Seem
to think that I've seen them in Ikea. Go take a look at their website

I'll have a look. I was aware there were options like this
available commercially. But, assume they will be way too expensive
(based on normal rates of markup)

On Sep 30, 12:55*am, D Yuniskis wrote:
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. *Typically, low profile fluorescent fixtures
are used in these places. *But, they often require
the addition of a molding to completely conceal their
presence. *This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). *While this would be an amusing approach, I
don't think it practical. *: *(I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. *This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. *The total light available would be an issue as would
the power requirements and the heat dissipation. *Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

FWIW, I needed to replace a bunch of very small 'wedge base' bulbs in
a digital readout with white LEDs due to unavailability of the bulbs
and high heat dissipation with the bulbs.
I found a source of 35 'delux white' T1 LEDs with diffusers and line
operated power module for $5. They should be in your stores soon,
since they are called LED Christmas light srtings.
The one curious thing that I found with them is that they have
noticably dimmed in the year that they have been operating. The
display is 'on' 100% of the time, but 90% of the time it is set very
dim and only is set bright when the room lights are on. Those LEDs
that are on most of the time in the display appear dimmer than those
that are infrequently on. I set the 'full bright' current to be less
than the LED current in the 'string'.

Neil S.

William Sommerwerck wrote:
I like the idea of recycling notebook backlights, rather than tossing them.

Building one from scratch is going to be pricey, because white LEDs have not
gotten really cheap. And all the ones I've seen have a bluish tinge which
might be disconcerting in the kitchen.

Agreed. However, I have seen large LED panels used for *outdoor*
lighting suggesting that it is viable (one up the street lights
the interior of a 15' x 15' ramada after sunset). Of course, The
City paid for those so who knows what the real price was! :-/

GE used to make "stick-up" fluorescents, which could be attached with screws
or double-sided tape. I don't think they're made anymore, but you might
look.

Yes, but they are too thick. Even using a very thin/long tube
(1/2") puts you at or beyond the ~3/4" recess available.
A CCFP from a laptop or a (page) scanner is *nice* and thin.
Maybe the solution is to just use the CCFL *tube* and omit the
LCD monitor's diffuser (then the inverter could be located
adjacent to the tube without fear of casting shadows into
the diffuser?)

GregS wrote:
In article , D Yuniskis wrote:
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

I used some led's and put the sink side inside a little circular
plastic dish. It actually some kind of laboratory specimin container.

Petri dish, no doubt ?

Its not perfect as I had to put some black tape around it so

I think if the lamps were in a linear array -- so that the entire
"light" was only 1/4" thick, 3/8" tall and as wide as the width
of the cabinet -- then you could tuck it up under the front edge of the
cabinet angled rearward and avoid much of the visibility issue
(unless you are talking about cabinets over a penninsula whic
could be visible from either front or back)

you don't see the light. I am using a moderate level of light, and they are
always on. I intend on hooking them up to battery backup,
along with the under counter bathroom lights I installed.
With the Cree warm lights, i get plenty of brightness using only 50 ma.
I had to use 100 ma. with some Luxeons. I am only using one lamp per couple feet of

"per couple of *feet*"? Is the amount of light you get
suitable as a nightlight? Or, enough to *augment* the normal
work light available in the kitchen (I want the added light to
be able to see things that are under the cabinets which are
invariably in shadow -- from the cabinets themselves *and*
your own body as you stand between the worksurface and the
overhead source of regular room illumination)

coverage. I also instaled an over the counter one in the bathroom, which
lights up the ceiling.

But this seems like it would be more of a "nightlight" role?

GE used to make "stick-up" fluorescents, which could be
attached with screws or double-sided tape.

It's called a Bright Stick.

http://www.thehardwarecity.com/getPr...ml?sku=5617816

On Sep 30, 3:55*am, D Yuniskis wrote:
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. *Typically, low profile fluorescent fixtures
are used in these places. *But, they often require
the addition of a molding to completely conceal their
presence. *This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). *While this would be an amusing approach, I
don't think it practical. *: *(I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. *This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. *The total light available would be an issue as would
the power requirements and the heat dissipation. *Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

I may have found just the thing you're looking for. Inexpensive LED
modules, 3 LEDs per module, low current, made by OPTEK and available
from Allied Electronics. They operate on 12VDC and come in various
colors including cool white. I use them for landscape lighting. Here
is a web page you can get all the info about them:

http://www.alliedelec.com/Search/Sea...mary&Ntt=ovm12

GE used to make "stick-up" fluorescents, which could be
attached with screws or double-sided tape.

It's called a Bright Stick.
http://www.thehardwarecity.com/getPr...ml?sku=5617816

Do they make an LED Bright Stick?

Great idea, but apparently not.

William Sommerwerck wrote:
GE used to make "stick-up" fluorescents, which could be
attached with screws or double-sided tape.

It's called a Bright Stick.
http://www.thehardwarecity.com/getPr...ml?sku=5617816

Do they make an LED Bright Stick?

Great idea, but apparently not.

(sigh) That was the point of my post...

nesesu wrote:
On Sep 30, 12:55 am, D Yuniskis wrote:

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

FWIW, I needed to replace a bunch of very small 'wedge base' bulbs in
a digital readout with white LEDs due to unavailability of the bulbs
and high heat dissipation with the bulbs.

This seems to be an increasingly common problem.

I found a source of 35 'delux white' T1 LEDs with diffusers and line
operated power module for $5. They should be in your stores soon,
since they are called LED Christmas light srtings.

Yes. But, how much light do 35 lamps give off when clustered
together? I've been playing with one-off lamps trying to gauge their
effectiveness and, without a focused reflector, they seem pretty
dismal. Note that you use CMAS lights differently than those
for general illumination. I.e., you look *at* XMAS lights so
even very tiny lights that give off very little light can
"look good". OTOH, you look *at* the surface that lights used
for general illumination shine upon.

Sort of like architectural landscape lighting: the lights
look bright but if you look at the *ground* around the lamp,
you can't really *see* anything! :

The one curious thing that I found with them is that they have
noticably dimmed in the year that they have been operating. The
display is 'on' 100% of the time, but 90% of the time it is set very
dim and only is set bright when the room lights are on. Those LEDs
that are on most of the time in the display appear dimmer than those
that are infrequently on. I set the 'full bright' current to be less
than the LED current in the 'string'.

Just to clarify...

You cannabilized the store-bought strings for the individual
lamps, right? And, prior to doing so, measured the current
flowing through the string (presumably the lamps were wired in
series?) to come up with the value that you then implemented
in your "incandescent replacements"?

So, it is not that the power source to the XMAS lights may
have aged. But, have you verified that your current (now dim)
lamps are still seeing the same current? I assume you just used
a fixed resistor in series with each?

rush14 wrote:
On Sep 30, 3:55 am, D Yuniskis wrote:

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

I may have found just the thing you're looking for. Inexpensive LED
modules, 3 LEDs per module, low current, made by OPTEK and available
from Allied Electronics. They operate on 12VDC and come in various
colors including cool white. I use them for landscape lighting. Here
is a web page you can get all the info about them:

http://www.alliedelec.com/Search/Sea...mary&Ntt=ovm12

These look pretty cool! But, I am a bit confused as to how they
are sold...

Pricing suggests that a "three lamp module" is the basic item
that you are buying (~$2.50). Yet, the datasheet indicates they
are sold in strings of 30 modules -- quite obviously *wired*
together. So, you're looking at a minimum purchase of ~100 lamps
(30x3).

I guess you are expected to "trim" the string to length
(but *buy* it in a 30 module configuration)!

In article , D Yuniskis wrote:
William Sommerwerck wrote:
I like the idea of recycling notebook backlights, rather than tossing them.

Building one from scratch is going to be pricey, because white LEDs have not
gotten really cheap. And all the ones I've seen have a bluish tinge which
might be disconcerting in the kitchen.


CREE warm white. You will like it, I guarantee it.
http://ledsupply.com/creexre-ww.php

I just bought an LED spot thats 120 vac. It too blue for
my tastes. Was about $20 on Ebay.


Agreed. However, I have seen large LED panels used for *outdoor*
lighting suggesting that it is viable (one up the street lights
the interior of a 15' x 15' ramada after sunset). Of course, The
City paid for those so who knows what the real price was! :-/


A friend just got huge outdoor sign which has red letters. They used white LED's.
They could have used red LED's an got much better coloring
All they use is white, so white it is. You can get some great
colors with LED's since you don't need filters and which also
dim.

The city was installing LED street lights here.

greg

GE used to make "stick-up" fluorescents, which could be attached with screws
or double-sided tape. I don't think they're made anymore, but you might
look.

Yes, but they are too thick. Even using a very thin/long tube
(1/2") puts you at or beyond the ~3/4" recess available.
A CCFP from a laptop or a (page) scanner is *nice* and thin.
Maybe the solution is to just use the CCFL *tube* and omit the
LCD monitor's diffuser (then the inverter could be located
adjacent to the tube without fear of casting shadows into
the diffuser?)

On Sep 30, 2:22*pm, D Yuniskis wrote:
rush14 wrote:
On Sep 30, 3:55 am, D Yuniskis wrote:

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. *The total light available would be an issue as would
the power requirements and the heat dissipation. *Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

I may have found just the thing you're looking for. Inexpensive LED
modules, 3 LEDs per module, low current, made by OPTEK and *available
from Allied Electronics. *They operate on 12VDC and come in various
colors including cool white. I use them for landscape lighting. *Here
is a web page you can get all the info about them:

http://www.alliedelec.com/Search/Sea...&Ntk=Primary&N...

These look pretty cool! *But, I am a bit confused as to how they
are sold...

Pricing suggests that a "three lamp module" is the basic item
that you are buying (~$2.50). *Yet, the datasheet indicates they
are sold in strings of 30 modules -- quite obviously *wired*
together. *So, you're looking at a minimum purchase of ~100 lamps
(30x3).

I guess you are expected to "trim" the string to length
(but *buy* it in a 30 module configuration)!

Nope, you can buy them individually from Allied (I did that for some)
or as many in a string as you want. And yes when I ordered 5 blue
ones they were wired together but I can't say that's going to be the
case all the time. The wires are fairly short when they cut a string
but can easily be wired together. You might want to just order a few
of various colors to see if they'll work as desired for your
application. BTW, if you do order some pay attention to the shipping
method for cost purposes. Some of the shipping options are kind of
costly. Double backed tape for mounting under a cabinet would be
ideal.

"D Yuniskis" wrote in message
...
Hi,

Motivated by the CFL thread, I'm looking for info on
fabricating "light panels" for use under kitchen
cabinets. Typically, low profile fluorescent fixtures
are used in these places. But, they often require
the addition of a molding to completely conceal their
presence. This reduces the working distance between
the countertop (which is fixed by the height of the
"base cabinets") and the underside of the "wall
cabinets" (which is fixed by the height of the ceiling!).

One amusing approach considered was to use the backlight
assemblies out of LCD monitors (i.e., remove the active
display and just use the CCFL's with the mechanical
diffuser). While this would be an amusing approach, I
don't think it practical. : (I'm not keen on having
all that high tension wiring around *water*!)

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. The total light available would be an issue as would
the power requirements and the heat dissipation. Cost,
of course, is also an issue.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.

Thanks!

I had the same idea, but used LEDs. I used lengths of
flat plastic conduit, with holes drilled at regular intervals
for the LEDs. Two lengths of wire run parallel inside the
conduit, each LED and resistor then soldered to these.
The conduit is hidden completely by the moulding under
the units, and it looks really nice when on. On reflection,
"straw hat" LEDs would give a better spread of light, but
it's quite nice as it is. Runs from a spare 12v PSU I had
lying around, and cost buttons.

In message , D Yuniskis
writes
Arfa Daily wrote:
"D Yuniskis" wrote in message
...

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.
LED 'tubes' for under-cabinet illumination, already exist, I
believe. Seem to think that I've seen them in Ikea. Go take a look at
their website

I'll have a look. I was aware there were options like this
available commercially. But, assume they will be way too expensive
(based on normal rates of markup)
Perhaps;

http://www.dealextreme.com/details.dx/sku.5256

There are plenty of LED strips on that website and they also have
flexible self adhesive LED 'tape' which you can cut to length (there is
a minimum length multiple though). I've uses them quite a few times now,
not the fastest if you choose the free shipping but they've never let me
down yet.
--
Clint Sharp

In message , D Yuniskis
writes
So, it is not that the power source to the XMAS lights may
have aged. But, have you verified that your current (now dim)
lamps are still seeing the same current? I assume you just used
a fixed resistor in series with each?
Unfortunately 'white' LEDs do dim over time, the phosphors used emit
less and light output goes down even when driven consistently at lower
than maximum ratings. The cheaper the LED, the faster they dim and also
the harder you drive them...
--
Clint Sharp

In article , Clint Sharp wrote:
In message , D Yuniskis
writes
Arfa Daily wrote:
"D Yuniskis" wrote in message
...

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

Aside from empirical testing, I'm at a loss as to how to
evaluate this approach without investing lots of time
and/or money.
LED 'tubes' for under-cabinet illumination, already exist, I
believe. Seem to think that I've seen them in Ikea. Go take a look at
their website

I'll have a look. I was aware there were options like this
available commercially. But, assume they will be way too expensive
(based on normal rates of markup)
Perhaps;

http://www.dealextreme.com/details.dx/sku.5256

There are plenty of LED strips on that website and they also have
flexible self adhesive LED 'tape' which you can cut to length (there is
a minimum length multiple though). I've uses them quite a few times now,
not the fastest if you choose the free shipping but they've never let me
down yet.

I was just looking at

http://www.dealextreme.com/details.dx/sku.5254

The main problem I had when they shipped requirng a signature.
Next time post man left it, but I did complain to the company.
Sometimes you will get back orders, and its confusing
on the documents.

I use their 350 ma. drivers that work off AC or DC.
Getting the right LED color is the main problems with
lighting. The Cree I mentioned fills the bill for me.

greg

On Sep 30, 10:32*am, D Yuniskis wrote:
nesesu wrote:
On Sep 30, 12:55 am, D Yuniskis wrote:

The next approach was a panel made of (white) LEDs
possibly embedded in some white/opaque plastic to
produce a luminous surface. *This would probably lose a
fair bit of light due to the diffuser.

Another approach was to just tightly pack LEDs in a
linear array (similar to a fluorescent tube in mechanical
design) and attach *that* to the cabinet underside.

But, I am unsure of how realistic such an approach would
be. *The total light available would be an issue as would
the power requirements and the heat dissipation. *Cost,
of course, is also an issue.

FWIW, I needed to replace a bunch of very small 'wedge base' bulbs in
a digital readout with white LEDs due to unavailability of the bulbs
and high heat dissipation with the bulbs.

This seems to be an increasingly common problem.

I found a source of 35 'delux white' T1 LEDs with diffusers and line
operated power module for $5. They should be in your stores soon,
since they are called LED Christmas light srtings.

Yes. *But, how much light do 35 lamps give off when clustered
together? *I've been playing with one-off lamps trying to gauge their
effectiveness and, without a focused reflector, they seem pretty
dismal. *Note that you use CMAS lights differently than those
for general illumination. *I.e., you look *at* XMAS lights so
even very tiny lights that give off very little light can
"look good". *OTOH, you look *at* the surface that lights used
for general illumination shine upon.

Sort of like architectural landscape lighting: *the lights
look bright but if you look at the *ground* around the lamp,
you can't really *see* anything! *:

The one curious thing that I found with them is that they have
noticably dimmed in the year that they have been operating. The
display is 'on' 100% of the time, but 90% of the time it is set very
dim and only is set bright when the room lights are on. Those LEDs
that are on most of the time in the display appear dimmer than those
that are infrequently on. I set the 'full bright' current to be less
than the LED current in the 'string'.

Just to clarify...

You cannabilized the store-bought strings for the individual
lamps, right? *And, prior to doing so, measured the current
flowing through the string (presumably the lamps were wired in
series?) to come up with the value that you then implemented
in your "incandescent replacements"?

So, it is not that the power source to the XMAS lights may
have aged. *But, have you verified that your current (now dim)
lamps are still seeing the same current? *I assume you just used
a fixed resistor in series with each?- Hide quoted text -

- Show quoted text -

I unplugged one LED from the string and used a 'scope to measure the
voltage across the LED and a clip on 'scope current probe to measure
the current.The string connection was somewhat obscure, and I did not
trace it out, but the LEDs 'appear' to be in series. However, when I
removed one it did not turn any others off. When I had removed the 24
that I needed for the digital display and then plugged the string in,
none of the remaining 11 LEDs lit.

In my application in the digital display, there is a DC power bus of
about 8V [bright] that feeds each LED through a resistor, and then an
'open collector' to common to switch the LEDs on or off. The light
sensor varies the voltage on the power bus.

Clint Sharp's comment " Unfortunately 'white' LEDs do dim over time,
the phosphors used emit
less and light output goes down even when driven consistently at
lower
than maximum ratings. The cheaper the LED, the faster they dim and
also
the harder you drive them..."
probably explains what is happening since these are likely very cheap
LEDs.

Without the diffusers, these LEDs are semi-spot and at a range of
about 40cm would give a softly defined light circle of about 20cm
diameter. One LED does not throw a huge amount of light, but 35 of
them do.

Neil S.