Click here for the previous post in this series.

03-Jul-18:

A quick twitter poll on Z9 Mini owners' breakeven expectations:

3 months is the target according to 59% of respondents. Even without fuel costs this seems optimistic. It assumes only a doubling in difficulty. For comparison, Dash experienced more than a 17 fold increase in difficulty over a three month period (counting from 1st Oct 2017).

9% expect not to breakeven.

09-Jul-18:

Today I moved country from having been abroad for a few months, back home again = 10.5 hours downtime.

10-Jul-18:

Z9 announced
Not more efficient, but is a cheaper purchase price per sol' per sec.

Investigated Economy 7 electricity tariffs in which rates are cheaper at night and higher during the day. Economy 7 works out the same as a standard rate for constant draw devices like miners. They increase the price of the day time tariff proportionally to the amount the discount the night time prices. Great if you work at night, pointless if you work 24x7.

12-Jul-18:

Second full ZEC arrived early this morning.

The noise of this machine is really a problem - if you have a garage, shed, vented basement or outhouse it would be okay, but it can't be lived with otherwise.
Soundproofing is difficult as airflow is so important for heat dissipation. Videos online show varying levels of success. I'll have to give it a try. Adds time and cost onto the project.

17-Jul-18:

The 10 day holiday of low difficulty (8.5->12m roughly) seems to be ending and we are now oscillating between 11-15m. My daily earnings, according to flypool predictions, are heading from around 0.16 ZEC to around 0.13 (-20%). The next set of Z9 Minis aren't due for another month or so, and apparently the Z9 full size machines will ship along side them (not fair!)

I discovered that Jaxx was an even worse choice of mining wallet than I expected. It isn't set up to handle large UTXO sets. Fortunately they include an 'export private key' feature which I used to port the wallet over to zcashd.

18-Jul-18:

YoungBuffalo has an iOS app for monitoring Antminers. I gave the developer access to my miner for a few minutes so they could update their app to be compatible with the Z9 Mini. I recommend the tool.

Soundproofing Pt. 1

19-Jul-18:

I drew up a design to silence the racket.
It will be a plywood box, with two layers of acoustic plasterboard lining. All three miners and the PSU will go inside. Lagged flexible ducting will be used to carry quiet air in and out of the box. I will add the materials to the overheads budget.

24-Jul-18:

For the last few days ZCash difficulty has been climbing more steeply than the previous few weeks. A large amount of hardware is coming online from someone. Maybe it's Bitmain testing the new Z9 or perhaps the Z9 Mini's which are to be despatched in a few weeks. If so the difficulty should drop for a while while they're in transit.
Looking at around 0.10 ZEC per day on the Z9 Mini down from a more stable 0.16 ZEC for the past few weeks

25-Jul-18:

Bitmain say they will publish 1st batch shipping data only.

03-Aug-2018:

I hit 5 ZEC today, but difficulty is rising quite a lot. 5 ZEC / 37 days = 0.13513514 ZEC per day on average, in line with expectations.
I mentioned earlier that Bitmain had been accused of swamping the Dash market with the D3 so let's take a look at the Dash difficulty graph for comparison:

If the same explosion in difficulty happens on ZCash it will be impossible to breakeven. It seems that due to the bear market climate causing low altcoin prices the difficulty slope is shallower than Dash's was at the start of the ASIC period. This is actually a good time to be mining for me, unlike miners who are having to sell their coins to cover overheads.

07-Aug-18:

Interesting discussion about GPLv3 licensing violations by Bitmain:
https://www.reddit.com/r/Bitcoin/comments/95p157/bitmain_violatin_gplv3_license_again_this_time/?st=JKMC4SPQ&sh=7f459a68

11-Aug-18:

6 ZEC reached

13-Aug-18:

Turned it off today for 10mins to rehouse it temporarily.
Had used 93.5 kWh over 10days and 3.5hours.

14-Aug-18:

Z9 was being really noisy, and summer temps have come down a lot in last few days from the >30 degrees to >20 degrees ranges - Something's wrong. It was also resonating a bit last night. Also noticed ASIC temps were not even, indicating some dust collection had started insulating things in places.

I cleaned it out, quite a bit of dust and fluff in there. PSU too (though less dust in it).
MUCH BETTER PERFORMANCE! Chips down from 73-68-72ish to 66-65-66 and fan down from varying between 3793 and 4200 down to 3480 stable. Phew.

16-Aug-18:

I switched energy tariff from £0.1615 per kWh to £0.1506 (incl. VAT). A small reduction but fixed until 2020 which seems sensible as energy prices are likely to rise, especially in the UK if the pound continues to devalue. There are cheaper green energy suppliers in the UK but they don't do variable direct debits or some other features I was looking for.

20-Aug-18:

Reached ZEC 7.0

Soundproofing Pt. 2

22-Aug-18:

Bitmain sent me two 55 USD coupons. No idea why - maybe something to do with helping the new KYC/AML medicine go down. Anyway...

I finally installed the single Z9 Mini in the soundproof box, what a relief!
At 10cm distance there is a -20db noise reduction. At 1m this registers as only a -10db reduction. Doesn't seem like much on paper, but I can now only hear it if I'm in the same room whereas before I could hear it in every room. I would say this does actually make a very small scale domestic ASIC mine feasible, but you need a multiple room flat at least. The soundproof box isn't small nor perfectly quiet.

23-Aug-18:

Overheads versus revenue update.

Building the soundproof box added on £110.25 (and a lot of time), quite an overhead for a very small scale business. Using prices from the time of each spend adds just over ZEC 0.72 to the breakeven point.

My breakeven targets in various currencies are now:
ZEC 17.00895876
GBP 3,186.33
USD 4,283.03
BTC 0.50755892
...excluding energy.

If I had all three units running it would take me 124.64 days to breakeven in dollar terms (assuming flat prices).

24-Aug-2018:

Mining profitability calculator results: 24-Aug-2018:

• ZECUSD: $131.04
• ZECBTC: ฿0.02006702
• BTCUSD: $6,565.68
• Difficulty: 16,340,958.01657120
• Electricity: £0.1506 kWh = $0.21 kWh
• Daily income: ZEC 0.30980935 (USD 40.82)
• Days to generate one block mining solo: 32.28 Day(s)
• Breakeven horizon: 124.64 days

Time Frame	ZEC Coins	BTC (ZEC/BTC at 0.02006702)	USD (BTC at $6,565.68)	Power Cost (in USD)	Pool Fees (in USD)	Profit (in USD)
Hourly	0.01290872	0.00025904	$1.70	$0.25	$0.02	$1.43
Daily	0.30980935	0.00621695	$40.82	$6.05	$0.41	$34.36
Weekly	2.16866542	0.04351865	$285.73	$42.34	$2.86	$240.54
Monthly	9.29428038	0.18650851	$1,224.56	$181.44	$12.25	$1,030.87
Annually	113.0804113	2.26918688	$14,898.75	$2,207.52	$148.99	$12,542.25

With just one machine running so far, I would have to mine for 374 days to breakeven. Note that difficulty at the time of the reading is a bit above the recent average and may return to mean for a few more weeks but obviously it will go up a lot over the coming months anyway.
In ZEC terms (what I really care about for the purposes of this experiment) I will have to mine for 164 days with one Z9 Mini, or 55 days with all three online.

As of today I have mined ZEC 7.53 which is 44% of my ZEC breakeven point. That's after 58 days of almost continuous work. Extrapolating that view means a breakeven duration of about 132 days in total so I would have another 74 to go assuming no difficulty change and not plugging in the other two miners.

26-Aug-18:

Graph of income with trendline:

The progress is remarkably stable so far but there is a detectable shallowing of the curve from about 22nd July.

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Next post: Progress update, in part 6.