CMB16D-QC input power

[scubado]

I'm wanting to use two computer power supplies to power a CMB16D-QC brd, one on each bank. The question is how to deal with the common negative. Is it safe to use the black wire from each supply or use the black wire from one supply and only use the +12v wire from the second supply?

[Max-Paul]

Sorry but that made my eyes cross. I think what you want to know is this. You can do it either way. But I would if using two supplies that you put the yellow and black from one supply on one set of terminals and the yellow and black on the other set of terminals. Effectively one supply is powering up 1-8 and the other supply is powering up back 9-16. Now if you want to tie the blacks from two supplies this should not be a problem and I can see that if you want you could use the yellow on the loads for say 1-4 and the yellow from the other supply for the loads on 5-9. Now what you would do is take all of the positive leads from the loads and wire them directly to the yellow lead. Do not put the positive lead on the terminals, cause those are common with the power terminals on the board.

Hope that makes sense, and was of help.

[scubado]

My concern is this: if I connect the yellow and black from one supply for 1-8 and connect the yellow and black from the second supply for 9-16, according to the manual the negatives on the board are common. Will this cause a problem for the supplies if their blacks are connected to each other?

[Max-Paul]

I quote my earlier post "if using two supplies that you put the yellow and black from one supply on one set of terminals and the yellow and black on the other set of terminals. Effectively one supply is powering up 1-8 and the other supply is powering up back 9-16."

You wrote "Will this cause a problem for the supplies if their blacks are connected to each other?" NO problem.

[scubado]

Again, thanks for the help. I should be firing up the controller tonight to test my landscape lighting. I will post a video hopefully tomorrow night.

[Max-Paul]

Great, and good luck with everything working out as planned.

[JBullard]

The CMB16D DC cards have a common positive and the mosfets switch the negative, please wire your lights correctly if they are polarity sensitive

[scubado]

JBullard wrote:

The CMB16D DC cards have a common positive and the mosfets switch the negative,  please wire your lights correctly if they are polarity sensitive

I wished I had known this 6 weeks ago, before wiring 1500 led's by hand. I'm just a little over half way done rewiring my light tubes for the negative switching.

I also fired up part of one of my displays and discovered I'm going to need bigger computer power supplies for the high powered led's. I'm getting a little bit of a flicker in the one that is currently hooked up.

[Ponddude]

First off, 99% of DC control is done by switching the negative lead. That is how MOSFETs work. Remember, they aren't triacs like used in AC switching.

Also, is the flickering you are seeing because of the power or because of the PWM?

[Max-Paul]

Good grief,

The guy was talking about his power supplies and the card. At that point negative is still common....

Now once you start talking about loads such as LEDs, then the negative is switched. And the positive is common to all of the LED circuits.

So, the best way to discribe the outputs or channels of the card is to say that they sink, not source.

Below is spoken in the older voltage from positive to negative. Even though I use the word current. Not to be confused with the hole theory.

Sink means to return the current to negative. And to source means that the terminal provides current to the load/LEDs.

[Steven]

scubado wrote:

Will this cause a problem for the supplies if their blacks are connected to each other?

There is a potential problem if you have a set of lights with common positive, and some of the lights in this set are on channels 1-8, and others are on channels 9-16. In this case, you will be ending up tying the positives on the two halves together, which will connect the positives of the power supplies together.

If you have already connected the blacks (negatives) together, then you now have two power supplies connected in parallel. Depending on the power supplies, this could cause unexpected results, especially when the lights are off and the load is low.