Converting 24V 250W ELC to LED?

[eveares]

As some may know, I have some old disco lights what use 24V 250W lamps.

I have often wondered how easy will it be to convert these to super bright LED's.

For the one that has an ELC lamp in it (Geni Mojo Spin Master 1), I was thinking about getting the following:

https://uk.rs-online.com/web/p/visible-leds/7877093/ (Yes, I know a standard 250W ELC is around 800 Lumens)


Of course I would need to retorfit something like below to power the LED, rather than building my own capacitive dropper and facing the issue of having 24V to start with what is a lot less than the 36V Forward voltage of the LED.

https://uk.rs-online.com/web/p/led-drivers/1711608/

I would also likley need to buy a lens as it would be about 80mm further back than the front of the existing ELC bulb.


For the heat dissipation, I am planning to mount the LED onto a 1mm thick heat shield at the back of the light with a thermal adhesive pad.

On this 1mm thick heat shield what I have cleaned of the powder coating, I have mounted a stock intel heat sink that I have cut down by 40% so it will fit (Was to tall otherwise); this is right up against the fan blowing air directly on to the heat sink.

The heat sink can normally handle a 80W CPU, so at 60% left it should handle around 48 Watts; the LED at 35V @ 550ma = 19.25W, so should be fine for the heat sink right?

Heat sink is screwed on with thermal paste as shown below:

Heatsink in Geni Mojospin 1

• eveares
• 30 Apr 2018

Anyone see an issues in my plan or got any feedback to give?

Also what LED would I use to replace a 250W 24v GX6.35 bulb?

Regards: Elliott.

 

[ban-all-sheds]

I suspect that SIAS is the way for you to proceed re cooling. It is entirely possible that there are non-linear factors at work re surface areas, and almost certain that CPUs work at different temperatures to LEDs.

 

[Robin0577]

I think you might have a bigger problem with the optics than the cooling...

Correct me if I'm wrong, but I think the ELC is a pre-focused lamp and reflector assembly with a single filament end on to give as close to a point source as possible with a very tight beam angle?

A flat LED array with a >100 degree beam angle is a very different beast and unlikely to give you anywhere near sharp focus when used with a gobo or similar pattern disc.

 

[eveares]

I suspect that SIAS is the way for you to proceed re cooling.

Can you please elaborate what you mean by SIAS BAS, not heard that acronym before.

I think you might have a bigger problem with the optics than the cooling...

That's why I feel I will need a lens, need a lens that will convert the LED's 115° beam angle to 16°/17° based on the fact the first optic is 30mm in diameter and will be 110mm from the LED.

 

[bernardgreen]

You may find you get poor results when using filters to colour the "white" light from LEDs as the "white" light is often not the full spectrum. Peaks of Red, Green and Blue with little in between

 

[ban-all-sheds]

Can you please elaborate what you mean by SIAS BAS, not heard that acronym before.

Sorry.

Suck It And See.

 

[kzmx]

Hi

Did you got this done?

I have pair of stairville MV-250, those metal head 250watt ELC halogens.

I have planned this too, but have not found any suitable leds...

About the focus of the halogen. On my lamps, there is still manual optics that the laps can be focused..