Wiring two power supplies to 2 banks on 1 controller

[fasteddy]

According to AUS101 If you're using two power supplies to inject power you're bridging the -V, so what is the difference if you're doing it somewhere down a strip or directly between the two. As an example Let's say I use the same power supply for the controller which also powers the outputs. Then down the line I use a different power supply and tap the -V into the current -V but don't continue the +V with the new +V. I don't see the difference from bridging the two directly or down the line.

Two banks on the pixlite 16, which is the controller I'm using, also allows for two different voltages like 5v and 12v simultaneously. Would you still tie the -V together then?


Since Fasteddy wrote the 101 manual, I'm wondering what his thoughts are here? Thanks again everyone for your input!

The reason for this is because if you tie back at the power supply then you still may not eliminate ground loops due to the different resistance paths of the cable and the string/strip which then can still cause issues, by connecting the ground at the lights you ensure you have a balanced ground at the injection point


With controllers that have 2 banks or more like the pixlite, j1sys and Sandevices you will find that on the board itself that the ground is tied between the banks but the +V is seperated allowing you to have different voltages.

 

[nmiller0113]

Thanks to everyone with their great info and responses. I also got an email back from Jim at SanDevices today about why he looped the AC Ground to the DC -V. Here it is just for reference:

---------------

It is good practice and is generally advised except in certain rare cases.
The jumper from DC- to AC ground is to protect against the possibility of
a fault in the power supply that could provide a path between the AC line
voltage and the DC output. This could potentially result in the presence
of hazardous AC voltage levels being applied to the pixel controller and
pixels.

I know some folks don't agree with this practice, but it's a good idea to
have everything referenced to a common ground. The Ethernet connection is
isolated from ground, so the only way to insure that the pixel controller
(-) is tied to earth ground is through the power supply.

A question I get is why doesn't the power supply manufacturer provide the
connection between - and ground. The answer is that some applications may
require + to be grounded, and others, such as wiring power supplies in
series, or when powering sensitive analog circuitry, may not allow the use
of the ground connection.

---------------

 

[David_AVD]

Have a question about running different voltages into the one controller and thought I would post here as it is along similar lines.

Check out the ACL wiki for this kind of thing. It has diagrams of various situations. Example 2 is the one that seems to fit your case.