Anyone with experience of using LEDs for display lighting?

[The Wanderer]

I'm in the process of turning an old hall cupboard into a display cabinet. The cabinet will be floor to ceiling, nominal height of 2.3m x 1.2m wide, carcased - the walls aren't brilliant for display purposes, internally finished in a satin lustre ivory colour, two full size glass doors and two glass shelves, which should help with light distribution inside the cupboard.

My initial thoughts are for two vertical rows of white LED striplights hidden behind each architrave. I like the idea of LEDs because of the minimal heat dissipation.

Some questions:-

Am I going to be better off with a continuous strip down each side, or should i be looking at 3 pairs of strips, one for each display area?

How much useful light do LEDs give for this purpose?

Are the strips likely to be enough, or should I also be installing a couple of wide angle LED floods in the top of the cabinet

What is the colour like with white LEDs? Is it extremely harsh and cold?

[Dave Fawthrop]

|I'm in the process of turning an old hall cupboard into a display cabinet. |The cabinet will be floor to ceiling, nominal height of 2.3m x 1.2m wide, |carcased - the walls aren't brilliant for display purposes, internally |finished in a satin lustre ivory colour, two full size glass doors and two |glass shelves, which should help with light distribution inside the |cupboard. | |My initial thoughts are for two vertical rows of white LED striplights |hidden behind each architrave. I like the idea of LEDs because of the |minimal heat dissipation.

Saw some of those at Maplins, but not lit | |Some questions:- | |Am I going to be better off with a continuous strip down each side, or |should i be looking at 3 pairs of strips, one for each display area? | |How much useful light do LEDs give for this purpose? | |Are the strips likely to be enough, or should I also be installing a couple |of wide angle LED floods in the top of the cabinet | |What is the colour like with white LEDs? Is it extremely harsh and cold?

White LEDs are very *white*, a lot different from incandescent or warm white fluorescent or ordinary energy saving bulbs. The difference of having Leeds in a room generally lit by any of the above will be *very* noticeable. Get a cheap LED torch to demonstrate the effect. It is possible to get white florescent which match LEDs, but I am not sure where. I have some in a reading lamp I got from Lidl recently.

[Adrian Berry]

Cold cathode tubes are cheaper,look like very slim fluorescents,and are also available from Maplins.

[Ian Stirling]

The heat is about the same either with LEDs or halogens, it's just more spread out with LED.

I would consider 2 - probably dimmed fluorescant tubes down the sides.

First step is to work out how many lumens you want in there.

You need to put some sort of light source in there, probably 4 points, and see what it's like in various conditions.

[Ian Stirling]

IIRC, 2 quid for 2*12" CCFL.

12V 0.4A IIRC.

[.]

IME they are very /blue/ especially when compared to incandescent lighting. I have an LED torch with the option of 3 hyperbright LEDs,

6 hyperbrights and one incandescent bulb. you have to cycle through all three states to switch on and off and the /blue/ spectrum of the LEDs is in stark relief to the yellow of the incandescent bulb.

very blue, very cold.

[The3rd Earl Of Derby]

This is revealing my blueprints here,but what the heck.

I've been buying a couple of laptops offa ebay at silly prices only for the backlights and inverter supplys to add lighting to similair cabinets I have, these backlight flourecents are the thinness of a straw and a 12v supply to the inverter and the light it gives is good. ;-)

[Dave Plowman (News)]

Use fluorescents. They produce *less* heat - and even less if you site the ballasts away from the lamps where the heat doesn't matter.

[Guy King]

The message from The Wanderer contains these words:

Tends to be rather bluish, which can be a good thing if you're displaying glass. I had some in some shelves once shining down onto glass objects. Looked OK - but choose narrow angle LEDs and have quite a few.

[Dave Fawthrop]

|Dave Fawthrop wrote: | |> White LEDs are very *white*

Which is what *I* see.

|IME they are very /blue/ especially when compared to incandescent |lighting. I have an LED torch with the option of 3 hyperbright LEDs, |6 hyperbrights and one incandescent bulb. you have to cycle through |all three states to switch on and off and the /blue/ spectrum of the |LEDs is in stark relief to the yellow of the incandescent bulb.

What you are seeing is the *difference* between the light sources.

|very blue, very cold.

Colour is a very personal thing, we all see colours differently, and only know that red is red because we were taught that as children. When I was a kid at school, we had a talk from a bloke from the then ICI Dyestuffs Division. He had a simple sequence of deyed pieces of cloth from light green to dark brown, and another single patch which we had to match against one of the set. We all matched the singleton to different places in the sequence. That has stuck with me for years.

The human eye with the brain is a very strange combination. After a while it judges whatever it thinks is white as white, whatever the actual wavelengths of light it receives.

And that is not the mention colour blindness.

[.]

what I'm seeing is different wavelengths given out by those lightsources

it's totally impersonal, measured in Kelvin's.

[Ian Stirling]

Not really. Kelvins only works for black body sources, that act like a hot object radiating light. For lights that are not black bodys, such as LEDs or fluorescant, it's a hell of a lot less clear, as the spectrum diverges considerably from a proper black body. Objects can look substantially different under lights of nominally the same colour temperature and brightness.

[.]

all true but 'white' LEDs still look blue, not white.

get away, really ?

[Andrew Gabriel]

Depends on the circumstances. They will look white in midday sunshine. They will look blue when the ambient lighting is lower colour temperature and dimmer, like sunrise or sunset, or artificial lighting indoors.

[Dave Fawthrop]

|Dave Fawthrop wrote: |> On Mon, 20 Mar 2006 18:31:18 GMT, "." wrote: |>

|>> Dave Fawthrop wrote: |>>

|>>> White LEDs are very *white* |>

|> Which is what *I* see. |>

|>> IME they are very /blue/ | | | |> What you are seeing is the *difference* between the light sources. | |what I'm seeing is different wavelengths given out by those lightsources | |>> very blue, very cold. |>

|> Colour is a very personal thing | |it's totally impersonal, measured in Kelvin's. | Kelvins are a *temperature* scale.

[Ian Stirling]

Then there are 'warm white' LEDs, which actually exhibit a tungsten-like spectrum, without much obvious blue peak at all. Not quite as efficient as the cool blue ones.

[Dave Plowman (News)]

Best one is to get some form of light box - or even a decent CRT - where you can adjust RGB to give any colour. Then try and match a narrow band light source like the old sodium street lighting. No two people will agree.

[.]

[Dave Fawthrop]

|Dave Fawthrop wrote: |> On Mon, 20 Mar 2006 19:35:26 GMT, "." wrote: |>

|>> Dave Fawthrop wrote: |>>> On Mon, 20 Mar 2006 18:31:18 GMT, "." wrote: |>>>

|>>>> Dave Fawthrop wrote: |>>>>

|>>>>> White LEDs are very *white* |>>>

|>>> Which is what *I* see. |>>>

|>>>> IME they are very /blue/ |>>

|>> |>>

|>>> What you are seeing is the *difference* between the light sources. |>>

|>> what I'm seeing is different wavelengths given out by those |>> lightsources |>>

|>>>> very blue, very cold. |>>>

|>>> Colour is a very personal thing |>>

|>> it's totally impersonal, measured in Kelvin's. |>>

|> Kelvins are a *temperature* scale. |>

||oh, dear, poor dave :-( | | temperature is totally inappropriate for measuring the wavelengths light from LEDs. What colour temperature is a green LED?

>>5mm Violet LEDs - 5mm Blue LEDs - 5mm Blue-Green LEDs - 5mm Green LEDs -

5mm Yellow-Green LEDs - 5mm Yellow LEDs - 5mm Orange LEDs - 5mm Red-Orange LEDs - 5mm Amber LEDs - 5mm Red LEDs Toshiba LEDs

[.]

I don't care ! but here's some reading matter for /you/ ;-)