Power Injection T's

stevelee

New elf
Joined
Dec 27, 2020
Messages
48
Not a power supply question, but rather a Power Injection T one.

To the best of my current understanding, If I power inject and use a different power supply that the first, I should use a T that doesn't continue the V+ through the T.

If I am power injecting with the same power supply, I can use a T that does continue the V+ through it and I can also back feed power in the opposite direction to the data signal flow. My question is then, If I inject multiple times like this in to a prop, should each injection lead have the same length, so that the risk of overloading the ground wire is next to nothing ?

I understand, that If using multiple power supplies, connecting the grouds together at the power supplies can lead too overloading the ground the wires.

I'm trying to work out how many of each type of T to buy. But thinking I should just buy heaps of each. How many would be recommended for 5K pixels ?

Cheers
Steve
 

Jarrad33

Hmmmmm Pixels
Generous elf
Joined
Oct 8, 2019
Messages
138
Location
Brisbane
Hi Steve

I use my Tee's every 100 in most cases and Always remove the positive pin in the first tee other wise the first port of the prop will be overloaded. So yes either way you need to break the positive pin.

Injecting multiple times. Watch this video
View: http://videos.xlights.org/xessentials-power-injection-made-easy_aa614f962.html


If you work it out on every 100 Pixels, you will need 50 off them. But this will depend on the prop of course
 

TerryK

Retired Elf
Joined
Feb 9, 2020
Messages
395
Location
West Central Ohio
"To the best of my current understanding, If I power inject and use a different power supply that the first, I should use a T that doesn't continue the V+ through the T."
Yes but one needs to make sure that the power through the Tee to the string routes downstream (away from the controller). A wiring diagram for the Tee will show the connection routing.

"If I am power injecting with the same power supply, I can use a T that does continue the V+ through it and I can also back feed power in the opposite direction to the data signal flow. My question is then, If I inject multiple times like this in to a prop, should each injection lead have the same length, so that the risk of overloading the ground wire is next to nothing ?"
If you are referring to the number of pixels, yes. Each power injection point would power the same or nearly same number of pixels. If referring to the length of the power injection cable, the cable length (supply to injection point) will determine somewhat the number of pixels that injecton point can power. The longer the cable length (greater voltage drop) the fewer the pixels.
Overloading of a V-/ground is I think not too common (no pun intended). Here, I do not feel a definite answer can be given unless 'what-if' scenarios are analyzed on the power system of a display.


"I understand, that If using multiple power supplies, connecting the grouds together at the power supplies can lead too overloading the ground the wires."
As just mentioned, possible but good wiring practices make such an event remote.

"I'm trying to work out how many of each type of T to buy. But thinking I should just buy heaps of each. How many would be recommended for 5K pixels ?"
The number is 1 less than the number of pixels per injection point divided into the total number of pixels. Depending upon the type of Tee used what changes is the point of injection.
For example - 500 pixels total and 100 pixels per injection:
Broken V+ Tee: 1st Tee at pixel 100 (feeds 100 to 199), 2nd Tee at pixel 200 (feeds 200 to 299), 3rd Tee at pixel 300, etc.
Connected V+ Tee: 1st Tee at pixel 150 (feeds 100 to 200), 2nd Tee at pixel 250 (feeds 200 to 300), 3rd Tee at pixel 350, etc.

In both cases the power to pixel #1 is from the controller and feeds pixels 1 to 99.
 
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