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Miniscan LED conversion


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Last week I mentioned that I was in the middle of building an LED conversion for my Clay Paky Miniscans. It isn't quite finished yet, but I thought I'd put a couple of photos so I can whet your appetites a bit and show you my progress so far.


The idea to attempt this project came about when I tried fitting an old 100 Lumen Lamina LED into a broken Geni scanner to see what effect its condenser optics would have on the light output. I had previously tried the same LED in a simple 3 lens projection system I'd made, but the only thing I managed to project was an image of the individual LEDs within its die. When I tried the LED in the Geni I was expecting the same thing to happen, but I was pleasantly surprised to see that I got a nice even beam out of the fixture. Even gobo projection was nice and sharp.


Encouraged by this, I found a 40 Watt LED on the Farnell website so I bought one to try in my Miniscan. I chose it because unlike other high-power LEDs, it can be run off a 24 volt power supply. Like a lot of other LEDs the one I chose is made up of several emitters on the same die, but they are wired up in two sets of six so each set of six needs 20-ish volts at 1 Amp. This does mean that I need two LED drivers, but I can use off-the-shelf drivers which makes things a bit easier.


To hold it all together, rather than try to modify the lens mount in my Miniscans I decided to make a new replacement lens holder which would incorporate the LED, its heatsink, and the drivers. Heres a photo of all the parts for the holder after I'd cut them out on my CNC mill :




Once all the bits are bolted together they look something like this:




The LED and drivers are missing from this photo as I need to buy a few more bits and pieces before I can wire it all up. The heatsink is a Thermalright CPU cooler. It doesn't have a fan of its own, partly because it sits directly over one already fitted to the Miniscan, and partly because if it did have its own fan I would need to find 12 volts to power it.


The holder is designed to be a drop-in replacement for the Clay Paky lens holder so no modification is required. This means that if it doesn't work out at least I will be able to convert back to a discharge lamp.

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Thanks for all the nice comments. Progress has slowed a little bit as its far too cold to work out in the garage at the moment. I can get most of the wiring done today though as I can bring that into the house. The power supply still needs to find a home as it is slightly too big to fit under the lens/LED holder where the fan used to be. It may have to sit on its side next to the lenses.


...whats the maximum thickness of cut of aluminium on that rig?


About 0mm :) Its a Roland PNC2300 desktop engraving/milling machine. While it would cut Aluminium, it will take until the end of time for it to complete anything. Its really meant for engraving/cutting foam, wood, modelling wax, and plastic. It will engrave onto Aluminium and Brass, but because its recommended engraving pitch (how deep it cuts on each pass) for metal is only 0.08mm and the cutting speed is 8mm/second, I wouldn't want to cut through a couple of millimetres of metal. As it is the plastic parts for my LED holder took about 5 hours to cut out, and the cutting pitch and speed are 0.2mm and 15mm/sec. respectively.


If you want your own machine you could always buy either this Roland PNC 300 or this Roland PNC 2100 from G and M tools who are based in West Sussex. I bought my machine from them last year, and I keep half an eye on their website in case another machine comes up. I am tempted by the PNC 300 but I don't have the space, the money or, if I'm honest, the need at the moment for another CNC machine. If you wanted a machine to cut Aluminium then the PNC 300 is the best bet as its much stronger, although the cutting area is much smaller than my machine. The cheaper PNC2100 is the little brother to my machine. It will struggle to cut metal, but is perfect for plastic or milling your own PCBs.

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  • 2 weeks later...

Having braved the cold out in my garage, I've finally managed to finish my Miniscan LED conversion and I must say I am very pleased with the results. Here's a few photos showing the output of my LED miniscan alongside an HMI300 Miniscan. Can you guess which ones which?






Green (apparently):






The LED Miniscan is on the right in each of the photos. Sorry for the poor quality. I'm not sure why the colours didn't quite come out as well as they should have. They are much more saturated in real life than in the photos. It might be my cameras white balance. The gobos were both focussed as sharply as I could get them, and most of the bluriness is down to the simplicity of the Miniscans single lens projection system. I think that tweaking the position of the LED in relation to the condensor lenses may help though.


The LED is noticeably bluer than the HMI lamp, which surprised me. I chose a cool white LED so I expected a certain amount of blue-ness to the beam, but not as much as I appear to be getting. Playing with the Miniscans in-built warm filter brought the LEDs apparent colour temperature down closer to that of the uncorrected HMI. I'm not using the warm filter in the photos. Without the aid of light meter (which I understand can be quite innacurate when measuring LEDs anyway) I can't give accurate figures for the light output of my LED conversion. However the brightness of the red and blue are on a par with the HMI lamp, the green is about as bright but slightly less vibrant, and the white is noticeably bluer and slightly dimmer. Obviously I get no output at all from the UV filter :)


Even though I removed one of the fans leaving the fan that sits under the ballast, my converted Miniscan is still a bit noisy. However I may be able to slow the fan down a bit as my LED runs practically stone-cold with the heatsink I'm using. While taking the photos I had both the HMI and LED minscans running for over half an hour. After turning them off the body of the HMI scanner was quite warm to the touch as you'd expect, but the heatsink on the LED wasn't even warm! I'm thinking that I may have over-specced the heatsink...


The process of converting to LED obviously means that I can remove quite a lot of parts which in turn means that my LED Miniscan ends up being around 2-3kg lighter than the original Miniscan. The conversion to LED means I'm using around one tenth of the power that an HMI Miniscan uses. Result!

Edited by gyro_gearloose
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very nice indeed!.. you say the converted one is on the right, which to my eyes actually gives a sharper gobo!

I did think in the earlier posts that the heat sink seemed rather, but considering if I had tried the project myself I would have ended up with a large pile of broken parts I didn't bother posting anything.


Have you done any calculations on how much money you would save on re lamping if you were to use the LED conversions for a number of years?

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Well the LED should last for 100,000 hours until the light output has dropped to 70% of its initial brightness. If we set a realistic life of around 50,000 hours to maintain brightness levels, then I would need 50 HMI 300 lamps. Assuming they are £75 pounds each, 50 lamps would cost around £3750. Now I know what I'm doing it would cost me around £120 in parts to make myself another complete LED unit consisting of the LED, the plastic body, power supply, LED drivers, heatsink, and nuts, bolts, and wiring. And power requirements are reduced to around 90W instead of 900W per unit.
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I've taken the larger of the two fans out (the one that sits under the lamp/lens holder) as it isn't really needed. I've kept the smaller fan, but had to turn it round so that it sucks air into the fixture rather than pulls it out. Its still a little noisy, though that could be solved by cutting out the grill which is cast into the body of the unit and replacing it with a wire fan grill. I'm not sure why Clay Paky didn't do this themselves as the holes they've left strangle the fans performance and create a lot of the noise by causing turbulence.
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This is a superb bit of work. Are you thinking with a big enough heatsink you could do away with both fans or is one cooling the original electronics? I have som TAS mini 2ultrascans. Really I should sell them as I do mainly theatre and fan noise does matter. But for certain musical type things revues etc. they would be great with a new life! By the way I see on Farnell it suggests 42v as a supply was this a typo on your part?

By the way having read the thread again I realise your picture is effectively a grown ups airfix kit :) Use humbrol paints to colour it to choice!

Edited by Nicktaylor
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The LED heatsink still needs a fan as without one it does get warm. Since I don't know that much about design cooling systems I have erred on the side of caution by using such a large heatsink, though I could probably slow the fan down quite a bit. According to the datasheet for the LED, the total thermal resistance for the LED and its metal clad PCB is 1.3 degrees per Watt. So, as I understand it, since the LED is 40 Watts the LED will reach 40*1.3=52 degrees above ambient temperature.


The LED is actually made up from two strings of six LEDs, so while the LED as a whole needs around 42V I only need to supply two 20-ish volt supplies. I've done it this way because LED drivers are more readily available for 24V supplies than 42V supplies.

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I've taken the larger of the two fans out (the one that sits under the lamp/lens holder) as it isn't really needed. I've kept the smaller fan, but had to turn it round so that it sucks air into the fixture rather than pulls it out.



I'm not sure why you have turned the DC fan around.

The Miniscan was designed to extract the air out of the unit as both fans extract hot air and pull new air into the unit via the fan grill above the lamp.

By sucking air into the unit, the vacuum is lost and warm air is just pushed around inside the fixture.


To be honest, I would've kept both fans in and as they were. Although you may think the mains fan will not play a vital role, you still have the stepper motors that heat up and it means you can have a smaller heat sink.


I'm very impressed though! Makes me want to convert my Miniscan's now!



p.s. Can you take a few more pictures such as the LED compartment sitting in the Miniscan and the LED itself and how it sits

Edited by Jamtastic3
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