Author Topic: DLA hub questions  (Read 1546 times)

Offline Steve Gase

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DLA hub questions
« on: January 06, 2015, 08:10:41 PM »
These are not the sort of questions that RJ would like to see asked on DLA, so I thought I'd try here...
I have some 5v strings that I want to drive with the uSC.

This past year I used buck converters to downgrade the power before the uSC from 12v to 5v.  It worked well except I occasionally overloaded the buck converters and needed to replace a few.

I'd like to make a change and use 5v on the DLA smart hubs...  I know that the Falcon 16 Port Hub would work for me, but I have lots of DLA hubs and would like to re-use a couple for this purpose.

So...  I see no reason that 5v input into a 4-port hub would not work.  Didn't try it, but there is no relevant circuitry so it seems like 12v or 5v -- it makes no difference.  right...?

The 16-port passive hub has me questioning whether 5v will work... I see (5) ST485BN chips and a capacitor...  what purpose do they serve?  are they regenerating the pixelnet for the output connector(s)?  if I used 5v would the board still work? 

The 16-port active hub presents even more questions... would the PIC be damaged if I used 5v input?  If I removed the PIC, would I end up with a passive?

The power situation is also interesting...  to get 5v into the board, I'd look at using the holes for the 12v option kit (not the power connectors from a PC power supply).  I wouldn't add the voltage regulator for generating the 5v to the ST485BNs and PIC.

Is there any value in using the DLA 16-port hubs for 5V, or will I just mess up the boards?
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Offline David Pitts

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Re: DLA hub questions
« Reply #1 on: January 06, 2015, 08:15:07 PM »
I think to use 5V you would first make sure the 5V is regulated. Come in where the 12V label is, remove 5V regulator and jumper across the input to the output of regulator. That would be my guess. Hvae not looked at whether the heat resistor goes to 5V or 12V but maybe remove that also. Is that part of the external 12V build?
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Offline CaptainMurdoch

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Re: DLA hub questions
« Reply #2 on: January 06, 2015, 09:05:45 PM »
Related but unrelated....

My simple EMT-mounted 8-string (folded) Technicolor v1 pixel tree actually survived this season up here in the rainy PNW and it has been outside for 5 weeks or so.  I have to issue my standard disclaimer that that was after letting it dry out all year in the garage and then putting 3 heavy coats of exterior grade enamel paint on all the wire entry points and keeping the original C9 covers over the LED's themselves and with the original buck converters running at 8.5V to reduce power after the SSC v4's.  I still have an unassembled Zeus 8 sitting here.  Even though I plan to build another tree, I'm going to see how long this one will last and am going to pick up a 9V power supply and use it to power the Zeus 8 at 9V to run the Technicolors so I can reclaim the SSC's and buck converters.

I also have some 24V 100mm "pixels" that need 24V.  The 5V regulator on the SSC v4 is rated up to 30V, so I may do the same thing you describe with a 4-port passive hub running at 24V to power those rather than having to do power injection out after the SSC.  I ordered a bunch of different colors of tie-wraps so I can start doing the color-coding of the cables to make sure I don't mix things up. :)
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Chris

Offline corey872

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Re: DLA hub questions
« Reply #3 on: January 07, 2015, 10:27:54 PM »
If done right, (ie pretty much what David says) I don't think you'd hurt anything.  The first thing which happens on the board is to step the 12V down to 5V  or 3.3V for all the chips anyway.  So just starting with 5V and tying the 5V reg input to output should power everything pretty much equivalently.    If you were going up in voltage, that might present some issues, but down to 5 should be safe.

The big ballast resistor is on the 12V line.  If you plan to use an ATX power supply, you might need to move it to an external 12V line to make the PS work, or your particular PS might work with it on the 5V line. 
Corey
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Offline Steve Gase

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Re: DLA hub questions
« Reply #4 on: January 07, 2015, 10:31:27 PM »
Thanks, guys!
I don't think I'll use the ATX supply since I want a lot of 5v power to drive the larger number of pixelnet output jacks.

Offline mms

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Re: DLA hub questions
« Reply #5 on: January 08, 2015, 08:48:23 AM »
It seems to me that PK said there had to be something else done to the DLA hub to allow for 5v and that's why we ended up going with the Falcon 16.  For the life of me I can't remember what it was.

 

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