Dumb LED Pars, for old dimmer packs?

(I already know this can be done, with a stupid-simple linear power-supply (transformer, bridge diodes, and a big capacitor) feeding the LEDs.)

So the qualifier here is, does American DJ or anyone else actually make dumb externally dimmable LED Pars?


The only problem I can think of, is that LEDs don't like power spikes and will die instantly where an incandescent lamp would tolerate it, so it'd probably need some extra circuitry to clip the line voltage in the event of a power transient.

- Dale

Well, let me start off by saying:

There's no way that such a unit would pass UL listing, combining multiple raw AC paths into a single ficture. Such a device would be a hazard waiting to happen.

Plus, with an LED, it's not just like a regular bulb where you plug it pretty much right into raw AC power as well. LED's go throught a transformer and are powered by DC power. But, it appear that ADJ is making colored LED Par 38's(not DMX), so no doubt there is something either in the bulb or the fixture itself handling this AC/DC conversion(for those about to light, we salute you!)

Another idea might be to just do what you're doing now, by using gels in Red, Green and blue to get the same results, and going with white LED replacement bulbs. But, I bet you're doing stuff with things like Par56s and bigger, and o the best of my knowledge, there aren't suitable replacement bulbs sold as an alternative to incandescent.

I hear ya. It's a good concept. I'd like to re-fit my Par38's with LED bulbs, even if just white, if I could just get the power savings. I'd gladly stick with gels, but if I could get them pre-colored, that would be acceptable as well. And in which case, I'd be doing something very similar to what you're doing.

Your idea is clever, but it's just not electrically safe. LED bulbs, where they do exist, are expensive. Let's say we're talking you're going to operate on a Par64. I suggest that because its kind of big enough to do this with. Assuming you can find the bulbs, you're gonna have to gut that fixture entirely and makesure you've installed proper brackets, receptacles and other fun goodies to ensure a safe, seated connection for the bulbs. Now, you're not going to get equal brightness as a white incandescent with a gel individually, but perhaps all three colors combined would do it. But, you've got the issue of needing some sort of light waveform guide to get a coherenent single beam of light that properly combines the three bulbs into one consistent light source.

Now, we've got a custom modified fixtured done by hand. Expensive.
Add to that the LED bulbs. Ouch, but probabl reasonable.
Now we need some custom optics and other goodies to add to that, and you're best off working with a real enngineer for that, and that is all going to be custom and expensive.
The power draw on the dimmer packs themselves is relatively low for them to operate, but they can pass some serious voltage. Going LED though, you'd still get that power savings even if the dimmer can pass it, the light won't draw it.


No, at this rate, it's not practical. Is the cost of $1200 for 6 dimmers really worth probably a LOT more in mods to get what you want? No,it's not. It's gong to be cheaper to just get things like the 6 LED Pro instead.

Want to save the investment? Re-deploy the dimmers for on/off applications to bring some DMX automation to "high tech effects".

We're in an industry where things move rapidly sometimes. We have to see when we can save investment and when we have to move on. Dimmers aren't going anywhere for a while.

It's not to say that your idea doesn't have merit. The ADJ Color Fusion does a similar task except via DMX: three halogen bulbs in the face of a wash fixture. But, the light itself, while very bright, isn't as great as I'd prefer. Mind you, I like this fixture, it's got a place in my rig and I'm glad I have it, but it just doens't have the type of solid wash I would prefer. But I get the same problem doing a similar concept with RGB mixing with my gel'ed Par38's. I know a lot of companies d "1 light, 1 gel, 1 color" type of methodology, but I don't have the budget and can't afford to do that. It makes sense: you want this "perfect blue" on your target, you can do that. Mix and match that with 3 cans and RGB gels, you can get the color, but it won't be as rich as you can't absolutely land those gel'd lights into a single beam.

What you think you're going to save on your investment you're going to lose in R&D, modifications and visits from the fire marshall. I don't recommend it. There are better solutions available that also let you leave your dimmer packs at home.

Keep thinking outside the box. I like how your mind works.

Large high-reliability computer servers frequently have two or three redundant power supplies, each with its own power cord, so there is precedent for such a design.

A 3-cord dumb PAR could be safely electrically isolated, if each supply were inside its own separate shielding cage, bringing out only the 1-5v DC onto the LED circuit board.

Meanwhile, each LED bank could have its own separate circuit ground for its individual power supply in the one fixture. This way any fault in one supply would be isolated from the others.

To me this still looks reasonably easy, inexpensive, and feasible to build.

- Dale

Let's also look at the costs involved in those high reliability servers, routers and switches. That costs money to do safely and properly AND get UL approval. But, only the power supply needs to get UL Approval.

In your case, you'd need the whole thing approved, and I know some of the process and similar things have been presented in the past, and they don't even test them, they just refuse it.

This isn't an apples to apples comparison. The precedent you state doesn't apply in this application.

You're talking about drilling 3 holes and cramming receptacle inside, with a rubber grommet around the cable. Or, something like a Socapex except smaller(I think there is smaller, less wires) to reduce cable input but do the same end result.

I don't know, but I wouldn't want to be anywhere near a stage that had something looking like that. I'd flat out refuse to work with something like that around me or the stage. Not to play the "jerk" card, but if I saw something like that on an event I'm working, I'd have your gear like that removed from the stage and taken out of production from the event before things would continue. In other words, it would have to be physically removed from the venue and left in an unplugged state. It's in my contract, and its fairly standard. Safety is not something taken lightly.

Let me know how it goes. You will find that if your stuff isn't UL approved, you're not going to be allowed to use it in clubs. Worse case would be if a fire marshall came in, he'd simply shut you down and tell you to get rid of those lights if they aren't UL approved. Worse case would you would be fined, but for that to happen, you'd have to ignore orders and do it anyways and that's easily avoided by listening to the guy who is forcused on safety.

I've yet to see even top of the line lighting have redundant power supplies. You're not talking about that. You're talking putting 3 100% independent and hopefuly electro-magnetically shieled units into one container. This isn't like a "carrier chassis" where you can slide blades in and they share some common resources.

As I said, it's a neat idea, but when you put in the LED bulbs of sufficient brightness to do what you need(and those ain't cheap), you find real fast that there are better ways to go.

You're not going to save enough money to make it feasible and you're only going to cause problems for yourself. And the bottom line is that for your application, a better wheel has already been invented. Sometimes it's OK to re-invent the wheel. In your case, ADJ beat you to it with a better solution.

Consider for a moment a Par 38 LED bulb, using a standard medium screw receptacle. That would at last check cost me $40 each, and I got 32 of those Par 38's. I can GET the Par38 fixture $30for two 2 fixtures WITH bulb. Providing the proper brightness in your Par64's(again, assuming), its going to cost a lot more than that per bulb, and 3 per fixture. Let's just say it's $150 for 3 bulbs. Now your power supply/transformer, mods and other customization. How cost effective is it now?

I don't see it being safe, smart or a wise thing. I'm not trying to sell you lights, I'm a tech. I'm trying to be safe.

Did you just submit this to UL for approval?

An relative of mine who works for UL just called me over the weekend. Someone submitted something very similar to what you're describing. It was not approved. Said he could approve them individually but not crammed into one fixture like that, bt even so, he said there was problems with that guy's transformer design.

So, just some smack of reality at an unusual timng. But, this isn't anything new, he's seen other similar ideas over the years.

Nope, I am not an industrial designer. I don't have access to the design tools or manufacturing processes needed to create an actual functioning product. I'm just a hobbyist and school network administrator.

But, if I WERE to build such a device, it'd probably look like this....











Yeah, if I were to make one, it'd be built something like that. Simple full-wave rectifiers, with isolation transformers for each input power connector, common ground across all.

It's easy to build, like I said, and it'd be safe.

- Dale

Very nice dale. are you sure you dont want us stealing your ideas? or other forum members? haha.
Sincerely, and happy Thanksgiving.

I really do not care. I long ago came to the conclusion that patenting is usually a waste of time unless the creator has the resources ($$$) to actually carry out the product design and manufacturing.

As such there is about zero chance I'll ever make any money off of this, so I am putting this "out in the wild" in hopes that someone ELSE will make it for me eventually.

- Dale

Well, the issue is still you'd never really get the three lights to act as one light without some specialty optics to help direct the light better.

Just,it would be less expensive to go with an 64 LED Pro.

The other purpose of patenting is to hold a design so you can sue the pants off anyone else who also comes up with the same idea. Then you can either sell or license the technology and get paid that way.