Thoughts on using AM Tubes for heating this winter, any info about undervolting?

[VirosaGITS]

I been trying to find information about this, the most relevant post i found was sidehack saying he would try to hack it, see what the efficiency it gets at different voltage and would then post the performance sheets at different voltage, i did not see any followup to this.

I dont feel like bothering Sidehack in private, so does anyone have information about this miner's design that could allow me to undervolt it?

[sidehack]

I spent some time starting to plot curves, but to get the kind of data I wanted was taking forever and I had other stuff to do.

I do have three Tubes running right now, undervolted to about 0.73 and 180MHz. I couldn't get much stable below 730mV but it could have been a software limitation. I only spent one evening testing what I currently have running.

[Finksy]

Hey Virosa,

I'll include some extra rosewill 120mm fans for it.  The factory fans are REALLY annoying, push-pull is the way to go with these but you may have to replace the main fans.

Sidehack I remember you posting a flat efficiency chart over a large frequency chart?

[VirosaGITS]

Hey Virosa,

I'll include some extra rosewill 120mm fans for it.  The factory fans are REALLY annoying, push-pull is the way to go with these but you may have to replace the main fans.

Sidehack I remember you posting a flat efficiency chart over a large frequency chart?

Aweh man, you're the best, thanks.
I intend on running them with the outside hair blowing in them to cool them off for a while but when it get colder, i thought it would be nice to mess around with volt, especially for efficiency.

I spent some time starting to plot curves, but to get the kind of data I wanted was taking forever and I had other stuff to do.

I do have three Tubes running right now, undervolted to about 0.73 and 180MHz. I couldn't get much stable below 730mV but it could have been a software limitation. I only spent one evening testing what I currently have running.

Does that mean the machine take -vddc voltage command or such? Because gaining a bit of efficiency i could run 2 or 3 on one 15a 120v, would be nice. So if the machine has a easy way to down volt, that would be very nice.

[Finksy]

I'm pretty sure that voltage control is only possible by using the USB-UART adapters GekkoSci were making along with a custom version of BFGminer if I'm not mistaken.  The BE controllers that come with it are archaic and finnicky at best (and can only run on GHash pool from what I remember).  In summary, the controller/firmware that came with it is a real P.O.S.

Edit: it's CGminer.  Here's the thread for the adapters: https://bitcointalk.org/index.php?topic=857048.0

[helipotte]

Voltage control on these means pencil modding, or changing resistors, or adding pots.  Can't be done in software.  At least not one that I know of.

I have one that does 300gh@300w.  The BE200 seems to be linear at 1w/GH.

The tube I modded bottomed out at 0.75V.  Below this too many chips where turned off.  Had to change each regulator individually, 8 per board.

[adaseb]

Is this that miner that's very wide and prone to starting fires?

[sidehack]

All three of mine light up every chip at 730-740mV.  Everything 720mV or lower and somewhere between a bunch and every chip was turned off. I soldered a 6.34K resistor over top of the 3.3K in the feedback divider which takes the core voltage down from 800mV. It's a TPS53355 (same as on the AM Cube, BTCGarden AMV2, S1, S2 and pretty much everything Rockminer) so the voltage is fixed by a resistor divider and internal reference. No software control, no manual adjustment without altering hardware.

The BE controllers have a botched stratum implementation that is hosed on most pools. It works on slush and mmpool, that I know of. My three are running off one of those controllers.

The burninating miner is the Prisma. Same ASIC, different topology.

[VirosaGITS]

Voltage control on these means pencil modding, or changing resistors, or adding pots.  Can't be done in software.  At least not one that I know of.

I have one that does 300gh@300w.  The BE200 seems to be linear at 1w/GH.

The tube I modded bottomed out at 0.75V.  Below this too many chips where turned off.  Had to change each regulator individually, 8 per board.

Pen modding would not be a problem, is that actually doable? If someone would kindly point me to the information i need to do this. If not, i'm not very familiar with soldering stuff, but i have a soldering iron, maybe i could do it?