a) https://bitcointalk.org/index.php?topic=38711.msg3454360#msg3454360


b) You are about to embark on a long, frustrating journey, my friend.

Thanks!

I doubt if the ones from your local store have the 3.5A PSU.  For that price, I'm almost sure they come with the inferior 400mA or similar PSU as sold on the Bay.  Have you verified it?  If they do indeed have the 3.5A AC adapter, I sure would like to buy a bunch of them from your local store.  Even with a 2.5A adapter, they'd still be dirt cheap.  Where's your locality, BTW?

I only populated the front ports because I have exactly 35 miners (i.e. 7 x 5 = 35) in hand.  I'll have more BEs coming in tomorrow.

A work in progress:



These are the 7-port hubs from MCM.  As you may have already noticed, these are just the generic hubs from China that's all over the Bay and sold dirt cheap albeit with less capable AC adapters. All MCM did was couple the hubs with better power units and marketed them.  I could have done better and further reduced the per port cost if I had put them together myself but I was in a jam as I was expecting more miners to arrive in a couple of days and I only have so much USB ports on my rigs.  I had to pony up for a 2-day shipping and for the applicable sales tax though which added a little to the per port cost but it's OK because I already ROI'd those extra expenses.  

MCM's site specified that the AC adapters are 5V 2.5A.  I then called tech support to verify the specs.  The gentleman literally called their warehouse while putting me on hold and came back on with the good news that it is in fact, a 5V 3.5A.  Here's a confirmation:



It supports seven miners with no issues; tested it for a few hours.  With all seven BEs hashing, the power units get very warm (an optimistically good indication that the internal heatsinks are doing their job of dissipating heat through the case) but one could still touch them for the longest time and not experience any burning discomfort.

The seven BEs registered 21W AC off the wall on a Kill-A-Watt while mining (100% load or thereabouts).  That's 3W AC for each miner.  Based on the BE's specified rating of 2.5W DC, that puts the AC adapters' efficiency at around 83% at 100% load; at 50% load (peak) it would probably be at least 85% efficient.  That's impressive for a wall wart.  If I'm not mistaken, this falls within the 80 Plus Bronze category.

I'm expecting a few more miners coming in on Monday and I intend to max them out and populate the two rear ports on each of them.  Here they are in action:

http://s1330.photobucket.com/user/visdude/media/MVI_0076_zps911be64e.mp4.html

Is what your saying if the red wire is not cut and you lose one power adaptor on a hub that  it will then want to overload the next hub's power adaptor and make it blow as well.

 I have a 5v 40a power supply coming, have my 5.5mm power plugs and more of the cheap 10 port hubs (like in the picture above) coming and plan on powering to start four 10 port hubs with the ability to add another four in the future.

I wouldn't get my hopes up with that one. They are all over ebay for cheap. I have seen specs on it stating 1Amp total. Also, the specs at your link don't compute. 2.5Amp cannot provide 500mA to 7 ports.

I guess for $6.75 it wouldn't hurt to give it a try though-maybe your comes with a different AC adapter.

http://www.ebay.com/itm/161054576343

http://www.ebay.com/itm/160691080418

Output: DC 5V 1000mA
Plug standard: US/UK/EU (choose the suitable adapter as you like)
Operation Systems: Windows Vista, Windows XP, ME, 2000, 98, Linux 9 and Mac OS 10.2 or above
Working humidity: 10% - 90%
Working voltage: 5V
Working current: 500mA

Yeah, this only powers 2 miners! I have one and hate it. I hope you did not buy any of these yet.

I have tried and using [ Monoprice 12-port USB 2.0 Hub w/3.5A AC Adapter ] in my setup I'm running 7 block erupters on it nicely and due to the nice round shape there is plenty of breathing room between all of the erupters for heat dissipation.

Monoprice 12-port USB 2.0 Hub w/3.5A AC Adapter

Updated on my hubs

I now have 3 hubs operational with 23 miners in total, 18 on my PC, 5 on my RasPi.

Power consumption of Raspi + hubs + miners + PSU less what is being leeched from the PC is 40W (or so my Watt Meter tells me, but I don't consider it that accurate...)

Hubs US$9.50 each (DX Bulk price FTW)
PSU US $34 (not from DX, sourced
DC plugs and cable US$5
Not burning my fingers soldering US$priceless

Once I have four hubs going, that's a total of $77 for 36 ports, or $2.14 per port - though I am tempted to limit the total used to ~32 to not stress the PSU (17A including the RasPi, out of 20A max), so maybe $2.41 per port.

Improvements to make - ~6A polyswitches for each hub (10 for $4 on ebay...)(the hubs have no over-current protection!), convert some more of my 30cm USB extension cables to power isolation cables, power the RasPi directly from the PSU, not from a hub.

Pics:
Hubs, Duct, PSU, RasPI.  The black power brick is providing the 12V for the Fans.  The PSU is now running very warm to the touch (still far cooler that an USB Erupter) with the extra 5 miners and RasPi.  Is was only warm before add that extra load.



miners all cosy in the duct.

$1,000 sent (BTC8.28BTC at the time): https://blockchain.info/tx/1eafe9977ac0954d091475bcead70bd2321672a15d70f4728cc4016f128fa66f

How did they come to accept it?