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Wiring and power of a RGB strip.


johnson8ryley

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So over the past few weeks, I've learned a lot about RGB and DMX. Probably to much if you ask me. I've got my parts listed out on what I plan to buy but the last question/problem I have is power and connecting the strips. I plan on replacing my 3 arches with these: http://www.aliexpress.com/product-fm/491662850-5m-DC12V-LPD6803-digital-led-flexible-strip-with-DMX-LPD6803-controller-waterproof-by-silicon-tubing-wholesalers.html. Now, I know you can wire each strip together but I've been reading a lot about signal drop and power drop with RGB strips. Does each strip need power and if so, how? Because, how would you wire each one together if each one requires power? Ive read about power injection but i have absouletly no clue how you would go about doing that. Do I really need to buy 3 of those or can i just buy 2 more strips without the controller? Also, if someone could recommend a cheap 12v power supply, it'd be much appreciated. Now, on with the wiring. I plan on buying the enttec DMX open which will then connect to my strips one way or another but I've seen/read that you connect via cat 5. What confuses me is the conversion of wires. The enttec pro is a 5 pin and the controller for the strip is a 3 pin so how does all that wiring occur? Do you convert 5 pin to cat 5 and then cat 5 to 3 pin? I know it's a lot of questions but I feel like I'm really on the right track here.

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You can find answers to almost all of these questions by searching the forums here, planetchristmas, and especially at auschristmas lighting where there is a ton of RGB info. You will have issues with voltage drop and channel limits that you need to watch out for. Remember each regular DMX universe (a single Entec dongle) can only have 512 channels. With 3 channels per pixel thats 170 individual pixels. You probably want to dig further into the configuration of the strip you are looking at (how many led's per pixel; how many pixels).

12v power supply selection depends mostly on how big (watts) and where you are going to put them.

There are sealed waterproof ones that can be $10-15 for 30-40 watts. Holidaycoro has one for $15; you can also find them on ebay and a variety of folks online.

If you are going to put it in a waterproof enclosure you have a couple options. There are nonwaterproof switched power supplies commercially available. Or you can take an ATX power supply from a PC and with some minor modifications use it as a several hundred watt power supply. Lots of times you can find these for free and there are a number of web sites, instructables, etc on modding these for bench use or for powering both 12v and/or 5v LED lights.

Hope this helps...

-Aaron

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Aaron thanks so much for the help. A big question I had that I forgot to ask was how many channels a RGB strip might have and looks like I should be able to cut it with the enttec open but if I were to add more smart/dumb strips in the future, how would I do that? Would I need the enttec DMX pro to daisy chain another dongle or would I just need another USB port to plug in another dongle? And I totally forgot about ausieschristmas. I started my research there but totally forgot to check there.

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You can cut them based on cut marks and chip spacing and end up with the resulting number of channels; the specifics can depend on your DMX to Pixel controller though. For example, there is a $15 controller Ray Wu sells that is hard coded to hear the number of channels its set to when you get it. So for example, if its set to 512 channels, and you only have 50 pixels on (which would be 150 channels - 1R 1B 1G per pixel) there isn't a way to pass the rest of the channels on to another controller. If you have the 256 channel version, you could send the first 256 channels to the first controller and the remaining 256 on to the second controller. With other controllers you configure them for how many channels they are listening for and then they will listen for those on the DMX side and send them down the pixel chain in the right format for the pixel chips used. Lots of info to be found on this - make sure you know what you want if you want to actually get what you want...

Number of channels per strip depends on the design and construction of the strip. I will illustrate a few main example designs below.

DUMB STRIP. 3 channels. All LED's are the same color at any given time. Whether the strip is 5 LED's or 300 doesn't matter. Still 3 channels.

A A A A A...


CHASER STRIP. 9 channels. Every third LED is on the same channel. Think of it like 3 interlaced strips. Whether its 9 LED's or 180 still 9 channels. All the A's are the same color, but the B's can be a different channel and so can the C's

A B C A B C A B C....


GROUP STRIP. 3 LED's in each pixel. Number of channels is equal to number of LED's (the math is LED's / 3 = Pixels; Pixels X 3 channels = Total Channels)

A A A B B B C C C D D D....


SINGLE LED PER PIXEL. 3 Channel's X number of led's. Could be as 450 channels for a 150 LED strip.

A B C D E F G H I.....



When you exceed 512 channels, you need a new DMX universe, which means a new dongle. This is true if you are using standard USB dongles and software like LOR to control.

If you are using other software, that supports e1.31 then you can get 4 universes and 2048 channels out of single devices...but too much about that to write here. Check out the aussie forums for sure if thats the direction you are thinking about going.

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So, if I'm not mistaken,  the ones I'm looking at getting (link in first post) is a single led per pixel *please double check for me* and it says there are 30 pixels so, I technically have 90 channels per string correct? Also, would I need to daisy chain the DMX controllers in order to insert power into each strip? I know that if you wire the strips together, the signal will be passed down from strip to strip but should I just daisy chain so they don't have a signal drop? Or, if I'm understanding you right, if I found a big wattage power supply, I could just inject a high amount of power in the first strip to avoid power drop?

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Honestly, I can't fully tell from that posting because part of it is in 'per meter' terms but its a 5 meter strip. You should email them and find out how many led's total, how many IC total, how many pixels total. As always, pixels * 3 gives you your channel count.

With a 5m strip at 12v, you should be able to inject power at the signal end and not 'notice' the voltage drop at the other end. I say it that way because if you put a scope on it or measure the MCD output of the LED's you can measure the difference, but most people - myself included - don't notice the voltage drop at the far end of a 5M strip. Go much further beyond that and you may start to notice. Put too many LED's in series and you will have not only a voltage drop problem but a total current problem relative to the rated and safe operating current of the wires being used to feed the strip and/or between the strips. Some quick electrical math - 450 5050 led's (3 strips of 150 each) will draw about 108 watts of power at full bright wight. At 12v, thats 9A running through the common anode! You start to need some decent sized wire to safely run 9A without melting the wire or insulation....and the strip itself may not be able to safely carry that much current. So if you are going to have 450 Led's, you are probably better off breaking it into different chains for power reasons even if the channel count didn't force you to do it already (referring back to the 512 channel limit per universe)

Voltage drop has to do with distance and internal resistance of the wire. Power supply size won't impact voltage drop; it only impacts how many chains of LED's you can power before you need another power supply.

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Well I can't edit my own message...but thats a funny typo in the middle

full bright wight.

I don't know what 'wight' is...but obviously meant 'full bright white'

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haha kinda figured that was a type but I might try out adding power at the first strip and adding power at the end of the 3rd strip. Hopefully each power source should be able to reach the center of the 2nd strip with little voltage drop. Unfortunately, I have no clue how to inject the power into the strip unless I have a controller but I'm pretty sure you can inject it another way. I don't need another dmx controller on the end, I just need a way to inject a power supply at the end of the power strip. Do I manually wire the power supply, buy a conversion, or do I go looking on ausieschristmas? haha

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hey Aaron and everyone else that reads this, I was messaging Ray Wu tonight and here's what he said:
Ray wu(2012-01-06 23:35:35)
i just called to my engineer
he said you can connect the 3rolls of the strip in parallel connection
he also suggested this power supply: '>http://www.aliexpress.com/fm-store/701799/209855560-289599951/350W-Dual-Output-Switching-Power-Supply-88-264VAC-input-12V-350W-output-CE-and-ROHS-approved.html

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If you wire them electrically in parallel, they will all mirror the behavior of one another. And there is also a question of what splitting the output current will do to the signal (definitely go check with the aussies on that). Lastly you still need to wire the power properly so as to avoid over driving your wires.

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Yeah I never really thought of what he was saying. I tried to explain to him that I wanted to connect them horizontally but I dont think he quiet understood what I was meaning. Unfortunately though, somethings still not clicking in my head. I understand that each strip will probably need power but how do I do that? Do I need to buy 3 strips with controllers so that I can daisy chain/inject power into each one? If that makes sense? I'm just trying to imagine how to inject power into each strip and still have each one daisy chained to another.

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Ok, The think that the OP seems not to understand and what I've been wanting to know myself is the wiring of the power supply. I understand injecting along the line, but do I HAVE to buy several power supplies or can I just buy 1 with a higher amperage and wire them all to one (Just not in a line)

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Buy a single 15-20 amp power supply and run some 14-16 gage wire down from it to the strips. Use SPT1 or SPT2 wire if available. Any smaller and you get a voltage drop. Use electrical wire nuts (twist-ons) and some shring wrap. Feed it to the front of each strip.

RGB power inserter http://www.ebay.com/itm/New-Repeater-Amplifier-RGB-LED-Strip-Light-12V-6A-/170749606818?pt=LH_DefaultDomain_0&hash=item27c1783ba2

Wire nuts: http://www.ebay.com/itm/Lamp-parts-lot-9-small-plastic-wire-nuts-TV-1552-/380278272420?pt=LH_DefaultDomain_0&hash=item588a59f1a4

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Ken Benedict wrote:

Buy a single 15-20 amp power supply and run some 14-16 gage wire down from it to the strips. Use SPT1 or SPT2 wire if available. Any smaller and you get a voltage drop. Use electrical wire nuts (twist-ons) and some shring wrap. Feed it to the front of each strip.

RGB power inserter http://www.ebay.com/itm/New-Repeater-Amplifier-RGB-LED-Strip-Light-12V-6A-/170749606818?pt=LH_DefaultDomain_0&hash=item27c1783ba2

Wire nuts: http://www.ebay.com/itm/Lamp-parts-lot-9-small-plastic-wire-nuts-TV-1552-/380278272420?pt=LH_DefaultDomain_0&hash=item588a59f1a4


Do you use these Ken? The Power Inserter.
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What's the wiring look like for the repeater for power and for the RGB? I know that youd have to wire it manually but do you cut those ends off or what? I totally understand how you would hook this up but I dont know what the wiring would look like.

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bdeditch wrote:

Ken Benedict wrote:
Buy a single 15-20 amp power supply and run some 14-16 gage wire down from it to the strips. Use SPT1 or SPT2 wire if available. Any smaller and you get a voltage drop. Use electrical wire nuts (twist-ons) and some shrink wrap. Feed it to the front of each strip.

RGB power inserter http://www.ebay.com/itm/New-Repeater-Amplifier-RGB-LED-Strip-Light-12V-6A-/170749606818?pt=LH_DefaultDomain_0&hash=item27c1783ba2

Wire nuts: http://www.ebay.com/itm/Lamp-parts-lot-9-small-plastic-wire-nuts-TV-1552-/380278272420?pt=LH_DefaultDomain_0&hash=item588a59f1a4


Do you use these Ken? The Power Inserter.


I bought several of these for a customer that needs 20 meters that all need to look the same color, but I like to break my color lines up and control the strips seperately. The power inserter above also "rebuilds" the R, G and B channels PWM signal, in addition to re-supplying power. This is OK for some customers.

I cannot find any of these devices for the Smart strips, but what I do is solder the +V and GND lines from the previous strip to the next strip and also to the power supply line that is running in parallel (some SPT2 wire) and do the same for the next strip(s). The data circuits stop at the end of each string. The next string is controlled seperately by a different controller. Just the power lines have a continuous run.
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Can I ask what the gnd lines? I'm still new at this and am still a little confused as to how you use that repeater.

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Smart strips have a GND line or solder tab.

Dumb strips do not have one; they have a constant +V (usually 12v dc) then the remaining wires or solder tabs are brought to ground voltage by the controller, as needed as per your programming in the LOR Sequence Editor.

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