Author Topic: Connecting power  (Read 1108 times)

Offline rcowan

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Connecting power
« on: April 09, 2016, 05:13:09 PM »
I won't even pretend to properly understand electrical engineering so I'm sorry if this question seems trivial. I'm curious about situations where the total amperage would exceed the fuse. I've posted a picture below that will hopefully better explain what I am talking about.

First, let's set up the assumptions. I know these aren't necessarily the real world numbers but the concept and theory will be the same. Also, this is assuming that the pixels are on full white.
Each pixel uses 0.05A
A strand of 100 pixels uses 5A.
The port on the F16v2 uses a 5A fuse.
I have 2 strands of 100 pixels for a total amperage of 10A.

In Option A below, only the data is connected between the two strands. Power to the second strand is coming in separate from the first strand. In this case each strand is on a separate 5A fuse. There should be no problems with this and it should be a safe option.

In Option B, however, the two strands have all 3 wires connected between them (12V+, 12V-, Data). Extra power is still connected to the second strand.

My question is this. Is option B viable for not blowing the fuses? Overall there will be 10A on the strand but I'm not sure if that 10A will be divided up between the two power inputs.

I've already wired up Option A and it's working fine (as I expected it to). I was just wondering though if Option B would also work.
Rick Cowan

Offline rcowan

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Re: Connecting power
« Reply #1 on: April 09, 2016, 05:14:38 PM »
Here's a new pic that will hopefully fit better on the screen.

Offline tbone321

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Re: Connecting power
« Reply #2 on: April 09, 2016, 06:24:48 PM »
Option B really serves no valid purpose and I would avoid it.  If you are going to power injection, then just use option A and be done with it.  With option B, if one fuse blows for whatever reason, the full load will be put on the other fuse which will cause it to blow as well. 

Offline rcowan

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Re: Connecting power
« Reply #3 on: April 09, 2016, 06:42:55 PM »
Thanks tbone. I kind of figured as much but I just thought I would throw it out there for educational purposes.

Offline AAH

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Re: Connecting power
« Reply #4 on: April 11, 2016, 02:29:58 AM »
My 2 cents worth is the B is better if you are attempting 2 strings of 100. With option A there will be limited voltage drop down the first string but the second string of 100 has no power injection point to the far end. As the rule of thumb is for power injection to be added every 50 pixels the 2nd string really is being shortchanged. I personally would prefer to use 1 fuse and have several heavy wires supplying the power to the start, middle and end of the 2 strings.

Offline tbone321

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Re: Connecting power
« Reply #5 on: April 11, 2016, 08:56:51 AM »
There really is no need for power injection every 50 nodes when using 12V nodes.  This is an issue when using 5V nodes and in that case I would also suggest multiple injection points.  This is the primary advantage of using the 12V strings. 

 

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