Topic: Block Erupter USB - Overclocking/ hacking ? - page 22. (Read 168756 times)

Who can tell me what resistors to replace and what resistors I can use to change voltage?

My approach here is that I would like to get a stable voltage range for oscillators that are easily attainable from well known trusted sources (such as digikey, mouser, element14, ect) and post a list of these with resistor values. That way a oscillator and resistors can be purchase and install with some certainty that it will work. Having a dialed in frequency at which is not obtainable in a oscillator package is not very useful. Now if we had these in bare chip form and were making custom boards we would be having a different conversation. I am more interested in dialing in the voltage at a given frequency as I think that will be more useful. The only road blocks here are I see are heat dissipation (which I think are mostly in check at this point) and current delivery capability.


Could you elaborate on this? My understanding is the resistors forms a voltage divider which offsets the voltage and is then compared to a reference the regulator then balances this to match providing a stable output voltage, that is the only effect the resistor has on the output. The inductor is fine up to saturation. So there will be a point at which enough current is drawn that the inductor will no longer be able to provide a stable output so far this point has not been reached. Temperature is much more likely to affect tolerances for the resistors than the inductor. As I express earlier in this thread I believe the inductor is good for current beyond what the voltage regulator is. Running at ~3 amps the inductor, on my board running at 447mhz, is not any warmer that the pcb itself.

Possibly it might be better to use an SPI controlled VCO

There are some really 'cheap' solutions available. That way you can have a bit of software that increases the clock rate until the thing starts producing too many errors, then you just gradually 'slide' the VCO back down a few tens of  KHZ

Take a look at silicon labs, they have a full range of products that can be picked up on ebay or group buys fairly cheaply.

What you will see is that the number of errors will increase as the frequency increases, so with a VCO you can 'trade off', also as the temp is a function of the speed you can slide the VCO Downwards if you start getting too hot, whilst still mining.

Only 'fly' i can see is If there is some sort of clock syncronicity between the USB circuit (UART/USB bridge) and the ASIC


As regards increasing the voltage/current... usually this is a resistor/inductor change......, changing the resistor will only get you so far, and if you get it wrong.. the flyback inductance from the mis-matched resistor inductor, will toast your PSU chip....

Then there is drift to watch out for.... as the  inductor works harder, the temperature rise (of the inductor) can take it as much as 20-50% out of spec, with a resulting change in the saturation levels
(sticking a small ram heat-sink on the inductor can really give a significant improvement if it is overheating)

Unfortunately I don't have a BE to experiment on, but I do have ~ 100 FPGA custom built farm, each of which is a bitch as regards over-clocking, and SM PSU ... bitchyness....

LOL yea huge fan of Ubuntu i've been using it since 5.04 but unfortunately Windows is a necessary evil in the IT world and thats what I have on my desktop.

I have a Bench power supply on the way so I should be able to get some accurate numbers on power consumption in a few days. My Block Erupter is still mining away @ 447Mhz it's been going almost a week solid. 

I heard its this program you have to uninstall everytime you buy a new computer.

What is this "Windows 8" you talk of? Haven't you heard of Linux

Got any info on which resistors I should buy while I'm getting the clock oscillators?

i know - friends here have the equipment, I have the miner *g*

I'm going to post some info here soon I may make a video or at least a how to with pictures. I just need to get a better idea on voltages/frequencies before I go making recommendations. You will most likely need more than a soldering iron if you're going to try this.

I would try it, but I need a little bit more detailed information.. like an "ifixit picture guide" what to desolder where and to solder on where, what tip to use and so on - i am a novice with the soldering iron

Thats pretty sweet, you should put a link to this thread up to draw some attention maybe we can get some more people willing to try this.

Well done congrats!!

oh wow my page was featured on HackADay
http://hackaday.com/2013/08/05/overclocking-your-bitcoin-miner/

BitcoinNerd is me BTW (do ya see the resemblance? )

o such fun

Watching and trying some bits myself

So I'm going to buy some oscillators and some resistors to play with.

Can you point me in the way of which resistors to use to increase the power? I was thinking about modding up to 18mhz (with steps of course).

Now that i cant build rigs anymore, this feeds my hobby urge. Just for shits and giggles

Thanks!

The lowest crystal speed that I was able to use without changing the voltage was 13.5 mhz. Wasn't much of a speed increase but was noticeable. Though with out changing the voltage resistors you may get more mining hardware errors.

I updated my page with this info

Wow and with all that you didn't answer my question.

Start with a Yes or No please then give your disclaimers and asterisks

Thanks

A good rule in life is: No, you can't get something for nothing. There is always a catch.

In this case you risk destroying your miner quickly, or possibly reducing its life. As the number of people who've tried changing the oscillators can be counted on one hand, we have no idea how long these modified units can run for. YMMV.