LED Lighting

[david.elsbury]

Hi there

I'm investigating the possiblity of making some LED lights, probably tubes and perhaps strips, because it's hard for me to get anything over here, and I just think that the existing stuff is far too expensive. Just for visual effect really, not as a tool for washing a stage.

 

I have a few questions relating to commercial units, if someone can help.

- Do most commercial units use seperate red/green/blue LED's or combined LED's?

- Using RGB mixing, how effective are colours such as yellow, magenta? Should the units I build have red/green/blue/magenta/yellow LED's to get the colours right?

- How long are most commercial LED tubes? 500mm / 1 metre/ other?

- Has anyone been here before and have any advice to offer?

Thanks :huh:

 

Regards

David

[Guest lightnix]

- Do most commercial units use seperate red/green/blue LED's or combined LED's?

They use separate red/green/blue LEDs. The combined RGB LEDs don't have sufficient output at the moment.

- Using RGB mixing, how effective are colours such as yellow, magenta?

They're not too bad, although you need a short distance (which will depend in the beam angle of the LEDs) to allow the beams to mix to produce the secondary colours. This can be reduced with the application of a light (e.g. Hamburg) frost to the front of the units. Deep shades of colour can be hard to achieve. I was asked to produce a very deep shade of blood red the other day - couldn't do it with LEDs :(

Should the units I build have red/green/blue/magenta/yellow LED's to get the colours right?

That's an interesting question and you're not the first one to ask it ;) Adding other colours to the mix would certainly increase the versatility of the units IMO and may well help them produce a purer white.

- How long are most commercial LED tubes? 500mm / 1 metre/ other?

Most of the ones I've seen seem to use metric "equivalents" of imperial measures, i.e. approx. 300mm (1'), 500mm (18"), 1.25mm (4').

- Has anyone been here before and have any advice to offer?

Without wishing to sound negative, by the time you've bought all the LEDs, designed and made the circuit boards, developed the controlling circuitry, written the software, made the casing, put it all together, tested it, debugged it, etc., etc., etc., you'll probably have spent loads more money (not to mention blood, sweat and tears) than you would have on buying something.

LEDs are current, not voltage driven devices, dimming them is generally achieved with Pulse Width Modulation. Varying the voltage in order to dim them doesn't work.

 

Have a look at this page, this page and this page from the "Things to Make and Do" section from the most excellent website by Big Clive.

Thanks :)

<{POST_SNAPBACK}>

You're welcome :)

[Richard Bunting]

Could be well worth talking to Howard Eaton Lighting, as they manufacture their own LED strips that can be cut into 4" sections. They also do all the necessary cabling and control to go with it. They do a huge amount of work in the West End (Chitty, Guys & Dolls, etc)

 

http://www.helluk.com/

 

Best Regards,

Richard Bunting

 

A.C.Lighting Ltd.

[Mush]

Should the units I build have red/green/blue/magenta/yellow LED's to get the colours right?

David

<{POST_SNAPBACK}>

 

Magenta LEDs don`t strictly exist, there are phosphor coated LEDs, similar construction to White LEDs, like Pink and Purple, but the phosphors can be very short lived.

 

Have a look at Craig Johnson`s LED Museum for a round up of available colours:

 

http://www.ledmuseum.org

 

Adding amber/yellow will allow a warmer white mix and adding more colours will obviously allow a wider colour gamut:

 

http://www.selador.net

 

Like PWM more than RGB will probably soon be subject of yet another U.S patent battle , sigh.