Yes, as philipma1957 said, I own one and so it is free - but my experience with a powered hub was not good - of course the spacing was too close so I could only plug in 3 Antminer U2/U2+ and the device dropped so much voltage that I had to feed it with 5.75 Volts to get 4.25 out - so as you say the hub needs to be capable of supplying current in excess of the USB2 spec and if you look on ebay they seldom give that information and maybe you have other problems if you use a USB3 hub.

The points made by alh are a valid criticism.  I had a cable to hand for a hard drive that took a normal male USB connector so that wasn't a problem for me and I used one of those Buck converters with a variable output one can buy from China or Hong Kong on ebay as it was before I found the Vinsic device (which as I suggested is quite nice for powering a number of PIs).

Naively (and correct me if I am wrong) but I think that a Pi with its 4 USB ports could handle 4 stick miners - subject to the following conditions:

Each stick would be attached to the pi by one of those USB cables that has an auxiliary power connector.
The auxiliary connectors would plug into a USB charger type device.

As an example I have a Vinsic USB power adapter that is specified as 40W and has 5 USB power outlets - so that a Pi and 4 sticks could be powered from the device.

http://www.amazon.com/Vinsic-5-Ports-Charger-Motorola-Cellphone/dp/B00L1XQBBM

I quite like this device which I have used to power a couple of PIs and charge a phone and a battery at the same time.

Whether this is sensible of course is another matter.

Maybe if you push the raspberry pi aspect of the project it could gain traction among users of the Pi and Pi 2.

Certainly if you are able to start making the stick miners I would use a Pi.  the B+ and the Pi 2 use less power than the original machine.

I guess that is a stripped down USB hub you have there on the wooden block.

I hardly ever bother looking at any other threads on bitcointalk now

They're probably prohibitively expensive and I'm not sure that throwing ever larger capacitors at the problem is a good solution but supercaps and ultracaps can store a lot of charge.

The IR3899 looks awesome and I had not appreciated that the TL494 doesn't have an inbuilt reference - thanks.  I'm still minded to try to roll my own software converter though (for 0.25V).  Last night I connected a 100W 660nm LED to a 24V supply and watched as the current rose from 4 to 4.3 Amps before I bottled out - later I got the spec from China and it said the Abs max rating was 3.5 A but it still seems to work fine.  It was attached to a 30x14 cm heatsink but perhaps it got to 55 Celsius - uncomfortable to hold so I'm going to need some fans ...

Keep up the good work - what you're doing is very interesting to hear about.

Thanks for the idea of the TL494 - I was surprised to see that the datasheet was last updated in Jan 2015 and there was an application note written for it last year http://www.ti.com.cn/cn/lit/an/slva666/slva666.pdf
I've only used the UA78S40 which is more expensive and available in fewer packages - so your device wins

Yes, of course, you are right. A pot on the stick miner and a DAC on the type zero strike the right balance.

I'm a minimalist and sometimes software allows you to remove hardware - but of course there's a price to be paid for that in terms of software complexity.
The basis of my metal detector is at http://www.rhodamine.eu/~richard/cv/ew.jpeg my only electronics publication

Thanks for the technical information
I am of course interested in what you are making - or I would not be here - but I think that switched mode design is very important for many other things - e.g. LEDs for hydro/aeroponics and electrolytic purification of Copper where, I believe a cell voltage of 0.25V is used - hence my interest in software design in place of standard chips.

Although I do not expect it, it would be interesting to see the schematic of your power supply design.

Although it is a completely different beast, there is a schematic for a software controlled DC-DC converter at http://www.ti.com/lit/ug/slau597/slau597.pdf page 36 - for the new MSP432 launchpad.

I pretty much gave up on switched mode power supply design many years ago when I found that the 25V EPROM programming voltage I generated had a 1 microsecond 14V overshoot that instantaneously killed my EPROMs.

I understand what you are saying and it is perfectly fair, but I said "why not also manufacture in Europe or China"

If you can't sell into Europe or elsewhere because of taxes or delivery charges then you lose nothing by also manufacturing elsewhere.

However, I applaud what you are doing.  Bitmain's U3 device used items that the home miner could easily source for themselves making it uneconomic to ship.  Do what you do best of all.

Don't forget us in Europe.  I know it is premature to say this but why not also manufacture in Europe or China.  Perhaps Olimex could make miners.  I seldom purchase from America as the delivery charges are often excessive.

Are (some of) these problems peculiar to Windows ?
Would people be better off purchasing the new Raspberry Pi 2 (quadcore Arm 7 + 1GB memory)

Thanks, that worked ok.

Thanks for the instructions


I tried this on its own:

and received

Surprising that Technobit requires their customers to do this rather than for them to arrange for it to be done just once.
Can you give me a link to the instructions.  Sorry if you have already published this.

Is the "technobit patch for cgminer" integrated into the official source code for cgminer yet ?

I have a raspberry Pi B+ and 4 U1/2s.  Three U2s are connected to a powered hub and the U1 is connected to one of the RPi USB ports.
There is a configuration change to allow the Pi ports to source 1.2A I recollect.  That suggest it may be possible to have 2 U2s connected directly - but I have not tried it.
My USB(2) hub is crap - with 3 antminers connected it drops a lot of volts - I think I'm feeding it with 5.7V to get 4.5V at the USB device.

With a B+ or the new Raspberry Pi 2 it might be possible to connect 2 U2s directly - but no more.

I ordered two.  Looks like a great bit of kit.

Looks authentic - photo taken 2015:01:12 15:28:21 in Binhai Ave, Shenzhen according to the EXIF information.

"The U3 utilises 4 of Bitmain’s latest generation BM1382 chips in high quality, domed case."

Doesn't look like a domed case, but more importantly the latest generation is the more efficient BM1384 so perhaps Bitmain is getting rid of old stock.