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Dinosaur
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I had no problem with the movie.
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Dinosaur
Originally Posted by
Excalibur
Second, movie's not loading for me. Sorry.
Originally Posted by
musicology
I had no problem with the movie.
Ah. IE won't load it, Chrome no problem, I now find. 
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I didn't go any further with that particular experiment. At the time the LED's, lenses and power supplies I needed to do the job weren't widely available. They are now, but sadly I don't have the fixtures any more. If I were to do it again.... it would be a single CREE or COB White LED attached to a small heatsink with a fixed lens and a constant current driver (now about a fiver - but unavailable at the time) replacing the 100w 12V switch mode pack that you find in the Dynamo's. I think I would have had reasonable success with that set up. LED's have also come a long way in the last 5 years, whereas white LED's used to be multiple RGB LED's built in close proximity, they're now usually Blue LED's with a phosphor coating.
A couple of points on this whole topic...
1. Safety... While you're right that it's all low voltage so it is (in theory) low risk, you still need a level of knowledge about cable ratings and how to connect and route cables within fixtures to make the end result safe so it is a) unlikely to burst into flames and b) unlikely to electrocute someone. If in doubt, ask a grownup (or someone with experience of electrical safety anyway) 
In case this isn't obvious, if you open up a fixture, it should be PAT tested before going back into service to ensure that nothing you have done has caused it to become dangerous. If you're talking about switching out existing SMD LED's for higher output ones, then you need a good working knowledge of electronics to avoid blowing driver IC's, turning resistors into charcoal or melting tracks on circuit boards
2. While it sounds like fun to turn a 100w Halogen fixture into a 100w LED fixture, when you go for these kinds of wattages of LED's there's a few things to consider. Firstly, the energy output from a 100w LED is actually enough to melt black plastic at close proximity so you need to consider the impact the LED will have on the inside of the fixture (especially if you can't focus all of the output through the lens so a lot ends up bouncing around inside the case). Secondly - you need to consider your audience - Looking at a 100w LED is roughly the equivalent of staring at a 750w halogen security light. Pretty uncomfortable - and actually dangerous to the retina. All of the pro fixtures come with PWM dimmers so you'll need to replicate this function somehow.
I'd be more inclined to go with something like 25w or 50w as a starting point - it'll be more than bright enough for most functions outside of arena grade productions Good luck though, and don't forget to share the results
Julian
Last edited by DJ Jules; 11-05-2015 at 07:34 AM.
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Good points Julian on upgrading existing LED fixtures and some things to consider there.
I do still think it is possible to interface the PWM drive from a 10W fixture to a 100W LED for example - at the end of the the day it is just square waves of various widths - Just the power delivered to the output device is increased so I would envisage you just need an extra 'output' stage, most likely power FETs - but yep I ain't tried it yet so there could be various hurdles I have not anticipated
There is not a lot of info on the various electronics forums about this...... so that makes it 'suck it and see' I think. However it is true as I said, that the component cost these days is low.. If you have any links to the availability of low cost CREE or COB LEDs I would appreciate the info mate.
All I can say really is that I will give it a go with that 10W invinceblED, or whatever it is that I have got my hands on ,as the optical path and heatsink positioning seem to be exactly right for this sort of conversion.
I need to order some components from China (cos it's cheap so doesn't matter so much if I trash a few LEDs in the process) but yes will post the info here as I go along, though it will take a few weeks to get the components here.
If anyone else on the forum is really interested in working on this sort of project and has some electronics knowledge it would be nice to be in touch with you, by PM maybe, so we can work together and compare results as we go along
Rich
Last edited by dicky; 11-05-2015 at 10:26 PM.
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Originally Posted by
dicky
Good points Julian on upgrading existing LED fixtures and some things to consider there.
I do still think it is possible to interface the PWM drive from a 10W fixture to a 100W LED for example - at the end of the the day it is just square waves of various widths - Just the power delivered to the output device is increased so I would envisage you just need an extra 'output' stage, most likely power FETs - but yep I ain't tried it yet so there could be various hurdles I have not anticipated
I believe (but I haven't checked) that you can get constant current drivers that accept a low current on/off signal and from what I've been told, this can be switched fast enough to create a dimmer using PWM. This is all theoretical though, I've never checked on the practicality.
Julian
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looked into doing this with a martin 812, trying to find a decent led to duplicate the light output with a decent beam was proving hard to do, they do have a bit of room inside and I recon it could be possible.
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Which is why I said 'interesting project for some of us'
, to be a good candidate to attempt the upgrade of a 10W RGB fitting to 100W whilst retaining all the standard fetaures. Hmmmmm......
