RGB Floodlight Problems

[Pecacheu]

I have a 30W RGB Floodlight from eBay, which I am trying to use with my LOR CMB16 controller off of a 12V signal. So far, I've gutted out the original controller and circuitry, soldered together a control circuit, bought a waterproof 30W Single-Color Floodlight driver, and stuck it all back inside. However, I've been experiencing some problems.

 

1. The red LED is brighter than the green and blue LEDs when all are at full brightness. I have tried 100k, 10k, and even 4 470ohm resistors (in both series and parallel). On the 12V side, none of them have enough resistance, and on the other, they have too much! If there is a configuration option to change the maximum channel percentage, that would work well. The red evens off with G and B at about 70% for warm and 60% for cool white, but my multi-meter refuses to measure the resistance at this percentage, probably because it's a PWM square-wave, and not an analogue signal.

 

2. The LEDs flicker on and off (about 2 times a second) at low brightness, but not if at least one LED is at full brightness. I believe that the problem is that the LED driver doesn't work unless it's driving 30W of LEDs or more. I think that it can probably be solved with a resistor or a varistor? But I don't know what wattage or how many ohms, and the math just confuses me.

 

3. My soldering iron died. So, yeah, not the best luck. Fortunately, there's a maker-space nearby.

 

Image of the circuit so far, taken with my trusty Logitech webcam:

[Santas Helper]

I have a question.

What was the voltage reading going to the LEDs before you hacked it? Measuring at the connecting point of the LEDs.

[Pecacheu]

I did not take any readings of the original controller, except to confirm it was indeed a 30W LED. Unfortunately, due to my hatred of non-open-able/modifiable embedded systems, the original sealed remote-control driver is currently a bit... damaged...

 

The 30W White LED Driver I replaced it with reads 33V right now, but it varies. According to the label, it can be anywhere from 24V to 38V.

[DocBrown86]

I am currently in the middle of a similar project using 20W floods off Amazon, and using the CMB24. I am using a 5W 15 Ohm resistor on the Green and Blue, and 10W 30 Ohm resistor for the Red (evens out the red to the other 2 colors). I am using 20V DC power supply. No power or brightness issues, but I am experience a random flicker, or flash may be a better description. Let's say I have red on full, every 10-20 secs blue and green will flash full for a split second, causing a white flash... Not sure what could be causing that. It also occurs with other colors, not just red.

 

If I have one, I'm going to try using a 120 ohm resistor as a terminator for the CMB24, as that DMX chain goes in about 4 different directions from the point I connected the CMB24. Hopefully that helps.

Edited December 20, 2014 by DocBrown86

[Pecacheu]

Anyone think that those resistors would work for my 30W flood? If not, what resistors would be appropriate?

 

I'm also going to be using 100W RGB LED Chips in a 3D-Printed DMX Light Projector I'm making. (Those things are insanely bright. The're even brighter then the 10,000 lumen bulb-based DMX projector!)

However, in that case, the DMX controller can calibrate the LED without using a resistor. But the 100W LED Driver suffers from the same "flashing" issue when dimming with only one LED on.

 

As for your random flicker, might it be caused by loose connections to the LED? Make sure they don't touch the conductive metal casing of the flood. Or maybe an improperly wired power step-up circuit, or bad transistors? It could also, of course, be a defective CMB24.

[DocBrown86]

I'm willing to bet a terminator may fix my issue (fingers crossed!). But all I have laying around is a 100 ohm resistor. Not sure if that will work or not.

 

100 ohm resistor had no effect on it. Still get the random flash of individual colors. When I disconnected DMX signal, the light stays completely off.

I do have Coro 3 channel DMX devices running on the same channels (running my current, dimmer floods out in my show), ie)160, 161, 162 (RGB). My DMX line is going to a junction point where it sends signal to the H Coro and to my CMB24. This shouldn't matter.

Seems to be behavior that is resolved by a terminator... Like the signal is getting sloppy or something.

And as for your 30W flood, I would say those resistors should work. The purpose of them is to bring the power down at the LEDs so that they don't burn themselves out from too much power. If they don't seem to bring them to the correct brightness, try a 15W, 60 ohm resistor.

Edited December 20, 2014 by DocBrown86

[Pecacheu]

Okay. BTW, I terminate my DMX runs with those 470 ohm resistors I mentioned and it works great. I just happen to have a bag of hundreds of them that came with LEDs.

I will admit, however, that I don't have very many DMX devices, but one I got cheap on Amazon is really noisy.

Edited December 20, 2014 by Pecacheu

[DocBrown86]

It had to be that. I'm betting a higher number resistor may have fixed it. I just switched the CMB24 from DMX to LOR protocol. Eliminated all of my problems!! Thanks for your advice tonight Pecacheu. Hopefully those resistors I mentioned will get yours working correctly.

[Pecacheu]

Well, I finally had time to go over to Radio Shack to get resistors a few hours ago. I couldn't find exactly the same ones, but after testing out combos of them in the flood (and running it for a while to make sure they don't overheat), I am using a 10W 50 ohm resistor for the red, but everything I've tried on the green and blue either starts melting instantly, or makes them too dim.

 

But with a resistor only on the red, I am getting a nice and balanced warm white. I have also tried various resistors between the + and - of the LED driver to fix the flickering (which the red LED's resistor has made even worse), and I found that anywhere from 50 to 100 ohms seems to work well. Unfortunately, even the 10W resistors (the biggest they had over at Radio Shack) were reaching 50 degrees after about 1 minute, although they would probably do better outside in the cold.

 

Do you think maybe combining 4 50 ohm resistors in a series-parallel grid would help? For high-power resistors, I currently have 1 50 ohm and 2 100 ohm resistors available.

 

(On an unrelated note, I got a new profile picture!)

Oh, wow, it is late right now...

[DocBrown86]

My guess on the heat problem is that you are using resistors that are way too small. The resistors I am using are based off my 20W flood, yours being 30W you would need to go bigger to prevent the heat issues... Also, out of the box my lights measured 14-20V depending on the color, at each LED. I am currently running a 22V power supply, as a 12V would most likely die rather quickly.

I did confirm that with my DMX line splitting so many directions, I would have needed a 450 ohm resistor to terminate it and stop the flickering, not 120 ohm.

Are you using DMX, LOR, or something else for comm? If you're using DMX you could put a resistor at the end of your data line rather then on the lights. If the problem persists, start adding them to the colors themselves. Nothing to the +, just one between the channel and each LED color. So the order will be at that point: Board -> Red Ch terminal -> 450ish ohm resistor -> wire -> bigger resistor -> LED. Chances are that the origional driver board has resistors inside it keeping the lights from going too bright. That's why it may be important to add them to each to prolong the life of your LEDs.

It was also suggested to me that if putting those 450 ohm resistors in line with each color works, might wanna upgrade to 1k, 1 or 2 watt resistors to prevent over heating. The joys of experimenting with resistor size...

Sorry for the info overload. Hopefully it helps!!

[Pecacheu]

I am sending signals over 12V from the LOR controller, so interference over DMX probably isn't the problem. The light also seems to flash if I use a smaller LED Chip than the driver is meant for, or, like I mentioned in the last post, if I put a resistor in the circuit. Also it's not like an instant on and off buzzing kind-of thing like my DMX things give me without a terminator, but instead it's more like it quickly fades on, then after a couple seconds it fades back off. But it was definitely flashing much less with that 50 ohm resistor. If only they had a 30 watt one...

 

Well, since Radio Shack has a horrible resistor selection, I think I'm going to try and string a bunch together and see if that helps with the heat. (So glad I got a temperature probe as an early Christmas present.)

 

Anyway, as for the extra resistors on G and B, I don't have enough high-wattage resistors for that apparently, so I guess I'll just have to make sure it doesn't stay on too long. I also think I'm going to double-up on the relays, just to be safe, since their data-sheet wattage rating is slightly below what my meter is showing the LEDs draw.