Kulp 16 A-B w/3 Power Supplies

[MikeH]

Hello, 

I have a Kulp 16 A-B setup with 2 12v LRS-600-12 Power Supplies. I want to add a third to mix for this season to support power injection. The Kulp 16 A-B has two connections on the board for power and both are filled. 

If I add a third LRS-600-12 and connect all grounds, can I just use it for power injection only? 1 supplies each to the two connections on the board and the third floating that just serves the power injection cables for some new props i added? Concerned about mixing two power supplies really. Not sure if its a problem or not. 

This ties into a question I've had for a year now. How do power all 16 ports and have enough power for something like a mega tree if the board only can take two power supplies. I'm sure this has come up before but couldn't find it via search. 

I'm fairly new. I started last year with about 3000 pixels and adding another 1000 this year. 

[tetleytealeaf]

Yes, you can do it.   But especially at 12V, you have to isolate the 12V pins from each other.  Probably the simplest way is, only connect 2 of the pins on some of the 3-pin ports on the K16.  Connect GND and Data, but leave VDD floating (but tie it off, of course).   Your third supply injects all of the power to those ports, but never routes through the K16.   The big thing is, the third supply can never "help" any single port.  It has to be all-or-nothing on that one port.   E.g. Port 15 has to be all PSU#3 or all PSU#2.  Not PSU#2 from the Kulp, but helped out by PSU#3 injecting on it.  

If you do, the symptom you will get is completely garbled data.  If so, don't panic, but you need to disconnect it and fix it.


You can also inject in the middle of a string, but the VDD at the beginning of the string has to end where the PSU#3 starts.  This is not as easy because you have to splice the string(s), but if you had to splice a pixel or two anyway, then this starts to make more sense.

P.S.  I actually consider connecting only the GND and Data pins on the controller an electrically superior way of doing it, anyway.  Because if any of the pixels ever shorts out in the weather, the current spike won't be going through your controller.  A few people out there in fact never connect the VDD pin on any of their ports, and rely 100% on power injection for everything.

[Poporacer]

If I add a third LRS-600-12 and connect all grounds, can I just use it for power injection only

You do NOT want to connect the grounds AT THE PSU. This does not solve the date degradation issue of using 2 power supplies. The V- needs to be tied together at the injection point.

supplies each to the two connections on the board and the third floating that just serves the power injection cables for some new props i added?

You do not necessarily need a third power supply just for power injection. Have you calculated your load to see if you even need a third one?

How do power all 16 ports and have enough power for something like a mega tree if the board only can take two power supplies.

Like I said, you have to calculate the load. If you are running 1000 pixels per port at 100% brightness you would need way more than 3 PSUs

I'm fairly new. I started last year with about 3000 pixels and adding another 1000 this year. 

Welcome to our obsession. With this # of pixels and running at the usual 30%, one power supply would be enough.

The big thing is, the third supply can never "help" any single port.  It has to be all-or-nothing on that one port.

That is not true. That would defeat the purpose of Power Injection.

If you do, the symptom you will get is completely garbled data.

If you do not tie the V- together at the Injection point, then you can get data degradation.

This is not as easy because you have to splice the string(s), but if you had to splice a pixel or two anyway, then this starts to make more sense.

They make Power injection Tees for this so if you inject in the middle and it is near a connection, just use a power injection tee (be careful! There are 2 types. Make sure you use the right on for your use case.)

Because if any of the pixels ever shorts out in the weather, the current spike won't be going through your controller.

That's what the fuses are for.

[MikeH]

I was looking at some other options, one is a Schottky, just before my fuse block to prevent it from returning. However, then I'd also want one on the v+ after the controller I'd think just to prevent it on that side. Im running at 50%. I could dial it down. 

Thinking forward though to a mega tree if i can convince the lady. And then thinking how do you power all those from one controller. Obviously there is more going on but I just dont get how you could control the number of lights off one controller without mixing power. 

I really dont want to cut v+ down the line if i can avoid it. Not connecting it all off the board might be an option. 

I do use 3-2-3 tees. Much nicer than splicing in power injection.  

Power injection is behind fuse blocks also. 

I probably over mathed the whole thing. The thought is going to be for future planning on a mega tree. Maybe I can swing one of the new kulp boards. I like how each bank of 4 is on its own power.

[jnealand]

First of all most mega trees can easily run at 30% brightness.  In fact in tests I have done 30% is about the highest you can go and still take a video that does not turn out with the tree looking like a big white blurb on the playback.  At the 10% the brightness is way down, but the colors looked better.  This season I have upgraded by mega tree from 3" to 1" spacing and from 1440 bullets to 4320 12v bullets.  That tree runs off 12 ports of a Falcon F16v4 running off a single server power supply.  3 of the remaining 4 ports have a 150 node star and 2 Showstopper trees of 400 nodes each.  I have 24 strands of 180 nodes per strand and use a Mattos "Spiker T" with each string to provide power balancing.  You are defintely over thinking the whole thing.  I did the same thing when starting in this hobby 20 years ago, but you will learn a lot of things as you gain some experience.  I avoid power injection like the plague but sometimes you just gotta.  And I really avoid any use of T's as I read too many posts over the years of problems with them.  Power balancing however is easy and just involves adding power to the end of a string which is much simpler and things like the Spike T make that easy and only involve the single port where node 1 is attached.  I have a second tree with 3200 EVOs (32 x 100 running off 8 ports) plus a star running off two meanwell LRS-12-350 power supplies.  You do not need a 3rd power supply.

[K-State Fan]

I run my pixel tree at 30%. My measured load on my tree 30% all white is 300 watts. 
I like Jim do not like to power inject but I also do not have any what I would call high density props and only 9500 total pixels. For me it works better to have controllers/power depending on location front, side and roof. I use a mix of controllers Falcon at the pixel tree and Kulp K8-PB and use a mix of differential receivers where needed. I started about 15 years ago with a 16 channel LOR controller. I have had more equipment over the years to remember but that is because I like new gear. I am sure my first SanDevice controller that I purchased as a kit would still work for what I have now but I can not resist new stuff when it comes out.

[MikeH]

Yep, probably time to reduce the complexity. When I started. It was a house line. 5v, 380 nodes left, 580 right. Injected every 100 nodes. Cut strings, soldered everything. Maybe for 5v I needed to. 

Last year, added the train set with matrix from GE 12v and injected using 3-2-3 tees every 200 nodes. The loco, coal and caboose are 700 or less nodes each. Passenger Car is 1150 or so. Every 200 nodes. 

Adding two windows outlines, plus mini tree with star. Have to say. I over did it. 

BTW, did i mention im power injecting everything with 14g wire? Might be overkill there too. Each prop had its own power injection run behind a fuse.

I do like redundancy, and when starting I always over built. Im learning, but I probably need to test loads without injection and see what the real voltage drop and power throughput is. Then build smarter. 

My first and only controller is a kulp 16a-b from Wired Watts in a 32022 bud box. Good setup but im going to move everything to a 32026 and lay it out how i want so I can get in and troubleshoot easier. Had some issues this year and the box is not setup right. It surely doesn't look like anyone else's. But 3rd year and have a better idea. Plus a 3d printer helps loads.

I appreciate everyone's responses. I dont feel there is ever one way, but multitudes of ideas gives me ideas for my own setup and I am grateful.