Led-Wiz and powered USB hub [noob question]

[modemman]

Hello, I'm a brand new noob with a (finally) finished arcade cab with X-Arcade tankstick and GroovyGameGear bling. I'm sorry to ask a 100 year old question again, but here it goes:

I'm trying to hook 8 RGB buttons and a trackball RGB light to a Led-Wiz. The buttons have the Helio9 modules and the trackball is lit by a RGB-Blaster board, all from Randy's store @GroovyGameGear. The Helio9 modules have 3 SMD RGB LEDs that consume 165mA at full power (according to published spec), so that's 1.32A, I round it to 1.5A conservatively. The RGB board for the trackball has 3 very bright LEDs, I lost Randy's instruction sheet, but he refers to it as the  equivalent of 12 superbright LEDs, so I'm assuming something like 30x12=360mA, let's say overall I'll be more than ok with 2 Amps if I want to run the whole thing at full power (not sure how much the controller itself needs, but I'm assuming not that much, those look like low power chips, I have the v2 one with the small chips).

Now, I get that the best/safest route is to tap into your PC's power, but I'm also looking into a powered USB hub, because (1) I'm running a very low power PC based on a miniITX with a very dinky power supply (2) I'm trying to reduce the number of wires coming to the tankstick controller - planning on cramming 2-3 Led-Wiz boards in there at some point - and (3) I already have these powered hubs from Staples which are tiny and have a very small and efficient 2.5A switching wallwart and will considerably eliminate clutter (and the inevitable wiring errors due to my stupidity and/or lack of caffeine in the system at the time of wiring).

What puzzles me is the fact that I know the USB spec limits current to max 500mA for USB 2.0 and 900mA for USB 3.0.

Question is - are powered hubs also made to limit current per port? Will I be able to get the full 2.5A out of my hub per port, or that is spread as 500mA per port as it is done on motherboards? So basically I'll just get dim LEDs and the bonus of not destroying my motherboard? Are there any hubs out there that "forget" to limit current? Should I just scratch this idea and just rig any decent high power 5V supply and run wires instead?

Thank you all for all the help - I've been reading this forum for a while and it's the reason why I'm in the hobby.

[RandyT]

The NovaTB-RGB trackball module is really about 18 LED's worth of output at full on, so take that into consideration.  I would skip USB power altogether for this kind of installation, and go directly to a decent, well regulated 5v supply.  Just make sure the ground side is made common with the LED-Wiz ground and it should be fine.

[modemman]

Thanks Randy!

Yeah, the trackball is really bright, I love that thing.

Will something like this do the trick (for one Led-Wiz board)? http://www.amazon.com/Power-Supply-ADAPTER-2-5A-D-Link/dp/B002FA5WE2

Are these little switching adapters reliable enough? Not sure how well regulated all these things are. I'm trying to avoid adding a full size computer PSU to my setup...

Why does it have to be well regulated anyway if I'm using external power for the LEDs? The board itself will still get power from the clean 5v from the computer, no? and the LEDs should be pretty tolerant? Am I getting this right?

Thanks again.

[RandyT]

Will something like this do the trick (for one Led-Wiz board)? http://www.amazon.com/Power-Supply-ADAPTER-2-5A-D-Link/dp/B002FA5WE2

It should, so long as the output isn't over spec'd.  Appears to be regulated.

Are these little switching adapters reliable enough? Not sure how well regulated all these things are. I'm trying to avoid adding a full size computer PSU to my setup...

They should be.  Just check the temperature of the unit after running it for a bit.  If it isn't getting too warm, or shutting down, it's probably fine.

Why does it have to be well regulated anyway if I'm using external power for the LEDs? The board itself will still get power from the clean 5v from the computer, no? and the LEDs should be pretty tolerant? Am I getting this right?

LEDs are very sensitive to over voltage/current.  The LED-Wiz gets power from the USB bus, but the LED's will be getting it from your external source.  If the LEDs are powered from the PC supply, that's already (or at least it should be) well regulated.  Wall warts and other supplies which are unregulated, will typically put out higher voltage than what they are rated at to allow for slump due to loading.  LED's typically do not put as heavy or as consistent a load on the supply, as the states are usually changing, thereby changing the load and with an unregulated supply, the voltage.  So regulation is important.

[modemman]

Thanks for all the cool info (and your very patient explanations), Randy.

I think I get it now (or at least I think I do).

[modemman]

Just a quick update, I ended up using this mini PSU:

http://www.mini-box.com/s.nl/it.A/id.417/.f

This thing is essentially a DC/DC converter (runs on 12V DC from a standard brick), very efficient (up to 95% with the proper input power) which for me means no heat (I can cram it into a rather tight and stuffy spot inside my cab). Its output is very well regulated (lots of folks reviewed this thing). Also, it meets the wife criteria, who asked me to do whatever to lower the electric bill - I intend to give this cab as much 24/7 life as possible. I looked into this years back when I was building an HTPC, but it was a novelty and hard to find at the time. It gives me 6A (8A peak) on the 5V rail, plenty to drive all of GGG's RGB goodness and I want to use the 12V rail to run some 5050 SMD RGB LED strips through another Led-Wiz. It's slightly on the expensive side (vs. "free" ordinary PSU from the garage/attic/closets), but I have plenty of 12V bricks laying around, so at least I didn't spend on that. And a new thought just came into mind - this thing would make a wonderful compact workbench power supply for testing and projects...

PS. Like any other computer PSU, in order to turn it on without a motherboard, you have to trip its load sensing circuit. Not sure if I'm breaking any "code" here, I know this was intended for a momentary switch and to stay on only if there's an appropriate load present, but I just jump the green wire (on a PSU harness) to the ground. On this little thing, it's pin 4 looking at the top row of the connector, starting from the left, with the clippy thinghy on top and I use one of the 3 pins to the right of it (all grounds), but you can find plenty of ground points elsewhere.

Next is figuring out Mala/Mame/LedWiz/Ledblinky/plugins etc. stuff... So much to configure, so much to learn.

[RandyT]

Interesting device.  I don't think you'll have any problems with the way you are forcing it on.  It's done all of the time with ATX supplies, and I haven't heard of an issue.  Looks like it has lots of power for other add-ons as well.  Nice find for powering bartops too, where space is a consideration.