Topic: Klondike - 16 chip ASIC Open Source Board - Preliminary - page 158. (Read 435376 times)

The underside of the ASIC has thermal vias to transfer heat to the heat sink. Almost all it's heat is dissipated thru the bottom. I still have to change this from 4x4 grid to 5x5 to optimize heat transfer.

The paste layer has not been checked by me yet and it has some changes coming under the ASICs. There actually has to be less paste there, and usually in a cross hatch pattern not just a big blob. The problem is that you can end up with too much solder under the pad and solder doesn't conduct heat that well. Usually under a thermal pad you use a pattern with spaces (cross hatch) to cut down on paste qty. I don't think kicad has support for this so I'll have to figure out what to do. I may have to add several smaller zones there or fix it after in the gerbers.

Hmm yeah that does suck...but I agree on avoiding the popcorn . I'm not sure if the X7R/X7S components could also handle higher temperatures during assembly, because there will be a lot of different techniques applied to get them on the board (skillets, IR-ovens, heck maybe even manual soldering). If they do support higher temps, that would be an additional argument for picking them.

I've gone through the nice KiCad files, and noticed that in the stencil (for paste) you've added only a minor blob of solderpaste to the center of each ASIC. Are you sure this would result in adequate heat dissipation to the PCB? I know that in theory the ASIC and PCB should touch, however, there could be minimal spacing which can be resolved with some soldering...
Looking at the bigger picture, the ASICs are designed to dissipate their heat to the PCB and not be actively cooled by a heatsink. Applying a heatsink to the plastic cast of the chip might not take away much heat at all?
I'm sure you've been thinking about this, so I'm probably wrong on the workings of the cooling, but maybe you don't mind putting my mind at ease ?

Kinda sucks that these cost 4x as much as the X7R. It's possible to save a little with X5R, and I don't expect > 85C. Blah, better to spend $0.53 extra total and not worry about ceramic popcorn...

yeap, this is nothing like an IKEA kit. You need to know some advance electronics to do it.

I'm looking forward to purchase a kit and test my equipment.. 

As most parts are SMD (surface mount device), they will require soldering. Guess there's no way around it, however, many folks around the world know how to handle that kind of work. I'd recommend getting someone else to assemble them, either a skilled person for low volume (manual) assembly, or a specialized person/business who will be prepared for handling many of the same boards using some kind of (professional/automatic) assembly-line.

Im in for 2 x K16 and 5-8 nanos DIY kits. If ready maybe need an assembly Steamboat offering.

 

I have less than zero skills when it comes to DIY.

Any chance we can get a lego like kit sans the soldering, i.e. part A1 goes into part B33 type thing?

I have tried soldering, it didn't turn out so well..........

You're welcome, and that's exactly why open source = good

Sorry about that. Just sloppy when I updated the parts list. I changed the value but not the product code. I'll fix that now. Thank you for checking. Believe me, I'm not infallible.

http://en.wikipedia.org/wiki/ATX

Supply voltage is to be within 5% or you can't be certified (don't put it past the cheap chinese PSUs you can find on ebay to cheat with that).

I think you're mistaking efficiency with V-delta. Your 80+ Gold certified PSU won't be that golden if you run it at 5-10% load. Check the box, the Gold bit should be specified within a range of power output.

Fox ex., the Enermax Platimax 1500 box states "90-95% efficiency at 20-100% loads". So it's not Platinum rated below 20% load.

If you invest in some expensive equipment, don't go cheap on the PSU or you WILL regret it

Ah yes thats better, nice. I've found also the C1005X7S1A474K, which is basically the same but with lower tolerances. Seems to be the same price though??

I noticed this also and substituted this one for it.

http://www.mouser.com/ProductDetail/TDK/C1005X7S1A474M/?qs=sGAEpiMZZMvQvaS66kI3TsXrxDUb6kFjGSZXVr8GtXc%3d

I think bkkcoins is intending on creating a 40x40cm version of the k16, to be called the k64. It is essentially the 4 of the K16's, and will probably save on a few parts.

i.e. only one USB connecter, maybe no klego pins, maybe less fan controllers, one power supply instead of 4.

Again, bkkcoins will correct me if needed.

Great work here BkkCoins, will definitely order when you have the DIY kit ready.

I've checked your repository and noticed something that made me wonder. Your order list is mentioning TDK C1005X7R1A104M (of which we'd need 174 pcs) in the 0402 package. When I check the TDK spec sheets, these are NOT 0.47uF as mentioned in the ordersheet, but 0.1uF. Is the spec off or do we need TDK C1005X6S1A474M? Note that in the latter case we'd move from thermal package X7R (-55 to +125ºC, ±15%) to X6S(-55 to 105ºC, ±22%).
Maybe I'm just off...hope that is the case as I'm obviously an EE amateur .

Edit: add spec link for your convenience: http://www.tdk.com/pdf/general_B11.pdf

Sounds great, because at one point i will have a good chunk of chips too.

What i wonder is, the K1 is similar to the Asicminer Erupter USB, the K16 is the standard setting and the K64 is 4 of these K16 put together. Whats the advantage of putting them together? Can parts be spared then?

I have read the recommendations about avalon miners and found this psu: Seasonic Platinum 1000
It seems to be a nice piece or work, you only need to put in the cables you need and it gets highest values in benchmarks. I think i will get one of these and hope it will be enough to run many or all diy-miners. Maybe, if needed, with y-cables. Unfortunately this psu never is sold cheap at ebay... i have an email alarm since a month without results...

What do you mean with layered into a 40x40? Double sided? So you put asics on both sides of the pcb? Wouldnt that mean a redesign is needed and more problems with the heat because both sides asics will heat up the counterpart too? Maybe you mean to put 4 of the K16 (each 20x20) put together and get one pcb that is 40x40? That would be the K64 then. but daisy chain? K256 would be 4 x K64 then? So 8x8 K16. I wonder if that really saves much parts. A K256 would mean 80x80 cm. Manageable probably. Maybe putting them in a rack like asicminer is doing it, putting some copper cooling units on the chips so that wind can flow freely through the copper and save space this way. I really would like to see such machine in my flat...

So at the end in reality there are only 2 models. The 1-chip miner and the 16 chip miner. Everything else is stacked together with the 16 chip miner. Then there must be a reasonable less needed parts when the K64 is $100 only while the K16 is $35 (4 x $35 = $140). Would be interesting to know if price drops for K256 or even a K576 with 3 x 3 K64 = 6x6 K16?

Now that i saw the pdf with the needed parts it looks like a good chunk of work again to create such miner. i hope my skills are sufficient.

It appears the ASIC has a PLL (phase locked-loop) on board to multiply the clock frequency. It takes 32Mhz input and manages to generate a higher speed clock internally that is selectable by a config word.

The supply voltage is not dynamically settable but can be controlled by a suitable resistor change. The purpose of changing the voltage would be to reduce power use and heat, and with less heat more stability at a higher speed. This will have to be determined once a working board exists and optimal values are chosen. It may be feasible to add a digitally controlled resistor to make the voltage adjustable but I'm not designing that in initially as it would be yet another variable to factor into debugging/testing, and potentially due to switching power supply design issues could cause headaches. When there's time later I may look at testing the idea.

It looks to be a configuration word sent to the board. I think the ASIC has an internal oscillator.

I should also say that bkkcoins will likely correct me very soon.

Right. That's 16 of the K16's. We need only 4 to get the equivalent of a K16.

Sorry

Yeah check that math.

I wonder how feasible overclocking will be. Obviously you could compensate with better cooling/heatsink design. Would one have to manually adjust the voltage, or is it software controlled?

64 x282 = 18GH/s

dont know where you get 72..