Author Topic: Power injection??  (Read 1588 times)

Offline lonewolf41

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Power injection??
« on: October 29, 2015, »
I am redoing my mini trees by using 97 pixels I just bought (purchased 100 count strings) from Ray.  I thought I remember seeing/reading that the new pixels from Ray used more power and that the old 128 node limit was no longer valid.  It is something less.  Couple of questions:

Is this true, and if so, what is the new limit?
I seem to remember reading that "power injection" could be used to circumvent this limit.  If so, how is this done with the pixels?  I have never done it before.  Is there a different pixel that would not require power injection?

TIA,
-Keith

Offline tbone321

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Re: Power injection??
« Reply #1 on: October 29, 2015, »
Even if the newer nodes use a little bit more power than the older ones, the string length that you are using still should be well within the max current output of the hubs ports.  Also remember that unless you are keeping the nodes on full white, they don't use their maximum current draw.  Power injection sounds like a big deal but it really isn't.  All you are doing is connecting another source of power somewhere along the string.  It is normally done by cutting the positive lead of the string where the nodes are starting to look dimmer and connect another power source at that point.  Ground is still ground so make sure to connect the grounds of the two supplies together.  I wouldn't worry about power injection until you test one of those mini trees and see if it needs it.  I would bet that it doesn't.
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Offline lonewolf41

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Re: Power injection??
« Reply #2 on: October 30, 2015, »
OK, thanks.  Just trying to prepare for the worst and understand it.  Also, I will only be driving 10 strings of 97 off one hub/supply so 970 pixels total.  Don't know if that matters as I don't know if it is a hub total power issue or individual string issue.  I think it is individual strings/nodes using too much power, but not 100% sure.  BTW, my CAT5 runs will be fairly short with 20'-30' the longest run so shouldn't get much loss in there.  Couple other questions for my information:

If I have to do injection, do I pull power from the same supply or do I have to get a new power supply?
What is the best way to get the power I need off one of the supplies?  Do I have to get an additional hub/power supply combo and run more CAT5 to the strings and figure out some connection type?
Any best practice on how to do it?
When you say connect the 2 grounds together, do you mean on the AC side, DC side, or both?

I realize this is only an issue for white, but I do use white a lot.  Hopefully this is all moot, but i just want to be prepared...and a little smarter.  I will get one of these strings onto test ASAP...in fact, I may just do it at lunch today to see what they look like.  If all 100 look good, then 97 should be fine for sure...I think. 

Thanks again for the help,
-Keith

Offline tbone321

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Re: Power injection??
« Reply #3 on: October 30, 2015, »
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OK, thanks.  Just trying to prepare for the worst and understand it.  Also, I will only be driving 10 strings of 97 off one hub/supply so 970 pixels total.  Don't know if that matters as I don't know if it is a hub total power issue or individual string issue.  I think it is individual strings/nodes using too much power, but not 100% sure.  BTW, my CAT5 runs will be fairly short with 20'-30' the longest run so shouldn't get much loss in there.  Couple other questions for my information:

The short runs are a help with cutting back on voltage drop but have no effect on excess current draw.

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If I have to do injection, do I pull power from the same supply or do I have to get a new power supply?

That depends on the reason for the power injection.  If the need is due to voltage drop, then you can use the same supply.  If the need is due to current requirements exceeding the power supplies ability, then another power supply will be needed.

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What is the best way to get the power I need off one of the supplies?  Do I have to get an additional hub/power supply combo and run more CAT5 to the strings and figure out some connection type?

There is no need for another hub even if you do need another power supply.  Cat 5 cable is also not required and would actually be harder to use.  Simple twin lead speaker wire is all that is needed and even then, that's if you intend to connect both the positive and ground connections at the injection point.

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Any best practice on how to do it?

There are a few ways to do it.  Too me, the best way is to separate out (not cut) the three wires between the two nodes where you want to separate the power inputs.  Then you have a choice.  You can either inject the power at this point or inject at the other end of the string.  I find it easier to inject at the other end of the string, especially when the other end is close to the input such as a tree or window frame.  In that case, connect the positive from the power supply to the positive lead on the end of the string and the negative on the negative side of the string.  Then cut just the positive wire on the string between the nodes discussed above and tape over the ends and you are done.

The other way which is used on longer runs is to separate the wires between the nodes as stated above. The difference here is that you will cut the positive wire and just tape up the positive wire coming from the previous node and connect your positive wire from the power supply to the wire going to the next node.  Then tap the negative lead into the negative wire and there are a few ways to do that.  You can use a crimp tap to connect the power supplies negative to the negative lead on the string or you can simply cut the negative wire on the string and reconnect them along with the power supplies negative lead.

The main points to remember is to make sure not to reverse polarity on the power leads and not to mess with the signal lead.  It doesn't really matter which end of the string the power is applied to as long as the positive is connected to the positive and the negative is connected to the negative.  The signal lead has to be connected to the input of the string.  If it is connected to the output side of the string, it will not function.  If you connect +12V to the signal input, you will probably destroy the first node an if you reverse polarity, you will lose the entire string.

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When you say connect the 2 grounds together, do you mean on the AC side, DC side, or both?

I am referring to the DC side and the two methods I told you about take care of that for you.  On the AC side, it is referred to as common and that is already done at the outlet.  Never connect any of the AC lines to the DC lines or you will release the magic smoke. 


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Offline lonewolf41

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Re: Power injection??
« Reply #4 on: October 30, 2015, »
OK, I put one string on to test at lunch using test firmware and I could not see any difference in the white color from node first to last.  The only thing I had was lots of flickering.  I think that was due to lead length if I remember, but at least it looks like injection is not required.  Crisis averted.  Thanks for the (thankfully unnecessary) help!!!

-Keith

Offline winwin

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Re: Power injection??
« Reply #5 on: October 30, 2015, »
Great explanations Tbone, Thanks!
AL.