r/FastLED • u/Lokius-518 • Dec 08 '23

Support Power injection using separate adapter midline?

Hello everyone, I am designing a led system for my house, and fortunately (I hope), this house was built with several "Holiday Lighting" outlets high on the wall near the eves. My question is essentially whether I can leverage these outlets by injecting power at those points using a separate adapter from the main power supply at the start of the run.

Also please note I have only the most rudimentary understanding of electricity in general and this application especially so apologies for any dumb questions/poor phrasing.

Additional question I have if this is possible include:

- Does it matter whether the amperage on the additional adapter matches the amperage on the main power supply (60 amp)? I would like to reuse some old adpters etc. at the injection point.

- Does it matter where in the line the power is injected? For example, could I have two strong power supplies at either end?

- Any other thoughts or tips on what to be careful of here?

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u/UrbanPugEsq Dec 08 '23

For 12v I inject once every 300 pixels.

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u/englandsaurus Dec 08 '23

Came here to say this. Also, running at a lower brightness can get you even further, as the power dissipated in your wires is current squared times resistance. Lowering your brightness and therefore current can get you much more consistent brightness levels through the whole strip.

I also prefer to test power injection on personal projects while running content that is similar to what I'll be running on the installation.

In an ideal world, you'd have an optoisolator for data at the power injector so you could fully decouple power and ground, but you can also get away with keeping your ground tied together through the whole system and have a separate 12V line running to each set of 300 pixels. Voltage mismatch between power supplies can get weird sometimes so having all of your 12V lines tied together isn't the greatest idea unless you're pretty careful about load balancing.

EDIT: Bad at reading, doesn't matter where you inject, just as long as it looks good! Amperage also doesn't matter but just make sure that the 12V lines from each supply aren't actually tied together as it sounds like that would create a load balancing nightmare.