perestroika
@perestroika@slrpnk.net
- Comment on Howto build 8-bit breadboard computer 1 week ago:
Very very impressive. :)
- Comment on Vertical solar panels help farmers produce both energy and crops 4 weeks ago:
Machinery comes is varying width. I would guess a farmer needs to decide at some point - is the priority using a 10-meter wide tool, or is it OK to settle with a 6-meter tool, or even a smaller one.
Basing on that, they’ll decide what the clearance between rows of panels should be. From an energy installation viewpoint, the shadow of one row should not cover another row during normal operating conditions. Assuming sun at 30 degrees elevation (“September on latitude 60”), the shadow of a fence that’s 1.2 meters tall will be about 1.75 * 1.2 = 2.1 m long. So from an energy generation viewpoint, one can pack things more densely than makes sense for farming.
- Comment on Solar panels between railway tracks? 4 weeks ago:
Also, costing €623,000 over three years sounds rather expensive for just 100m
It’s hugely expensive, but I expect most of the cost to be in the wagon that lays panels down and picks them up.
I doubt if this project will “fly”, however. A totally horizontal solar panel at ground level is a far cry from producing energy efficiently.
- Comment on solar PV → heat pump → water heater; direct, no A/C or intermediate components. Practical? Feasible? 2 months ago:
P.S. I have once used DC to power a pump “directly”. I use quotation marks because the pump (a water pump) was a brushless DC motor with an integrated controller. I used it on a field for removing water after a spring flood. Its controller accepted 24…48 V input, and it was powered from a 40 V solar panel brought on a wheelbarrow. :)
- Comment on solar PV → heat pump → water heater; direct, no A/C or intermediate components. Practical? Feasible? 2 months ago:
instead of powering the heat pump from the wall, the heat pump can be connected directly to a PV
I have no experience with this exact combination. I know that “batteryless” inverters exist, but most of them are on-grid inverters. In that scenario, all that matters is monitoring your production: if you don’t want grid energy, you only run your system when your PV produces enough.
Another type of batteryless inverters are “pump inverters”. Farmers seem to like them for pumping water from wells into water towers. A pump inverter can be configured to run at 50 Hz (or 60 Hz for North Americans) and 230…240 V alright, but it is not designed to power electronic devices, but dumb agricultural motors. There is considerable risk involved with powering a heat pump from a pump inverter, unless you find an exceptionally simple and dumb heat pump with very limited or resilient steering electronics.
Efficiency losses are small anyway, but mostly happen during battery storage or when voltage needs to rise or drop considerably (e.g. a transition of 700 -> 24 V or 24 -> 240 V would cause a small efficiency loss).
I’ve heard that a PV can directly power a compressor
This seems unlikely as the compressor would have to be a brushed DC motor. That kind of motors don’t last long, they wear out their brushes. But a brushless DC motor is essentially a three-phased AC motor already, just the controller (full of smartness and MOSFET transistors) accepts DC input.
If you have a good technical overview of your heat pump system, maybe you can locate a point where regulated DC can be fed into the system, but that would be hacking. Alternatively, maybe a niche market already exists for DC-powered heat pumps, e.g. for caravans, trucks or ships? But on niche markets, prices typically aren’t good for you. :(
- Comment on Swiss Researchers May Have Solved Hydrogen Storage 2 months ago:
it would (as far as i understand with high school chemistry) be strictly more efficient to electrolyse rust directly
I’m not a chemist either, but I do know a bit of chemistry.
Typically, you need a solution of NaOH (sodium hydroxide) to directly reduce iron oxide in an electrolysis cell. If your iron oxide contains impurities, those may react with NaOH and ruin the fun. Also, if you have exposure to CO2, your NaOH will gradually [degrade]www.aqion.de/site/182), producing NaHCO3.
- Comment on Exclusive: Sodium batteries to disrupt energy storage market | Oliver Gordon | July 1, 2024 3 months ago:
Well, for a chance - they are now actually in production, while 5 years ago they were in laboratories.
- Comment on Solar leading Baltic states to energy security 4 months ago:
Out of the three, Latvia has serious energy storage - a 4 billion cubic meter (at normal pressure) underground gas store, sufficient to carry all three countries over the winter.
But so far, it’s filled with fossil natural gas - but some day it could be filled with synthesized methane.
As a backup option, Estonia has oil shale - probably the worst fuel on Earth, so the price of emitting CO2 keeps those plants out of the energy market during summer. During winter, they come online though.
As for solar, we aren’t planning to rely much on that. Solar capacity has of course skyrocketed, but only because it’s very easy to install. But at latitudes 55 to 60, days are really very short in midwinter, so wind and waste wood are the likely candidates in future - after oil shale leaves the scene, but before synthetic gas becomes feasible.
Regarding pumped hydro - it can stabilize a day, but can’t stabilize a week or month. Lithuania has a biggish (~10 GWh) pumped storage facility. The rest of Baltics don’t have suitable terrain. Estonia has limestone banks, but they’re under various forms of protection and even if one built a lot of pumped hydro, the low elevation difference (up to 50 meters) means one couldn’t support the electric grid through more than a few days.
Regarding hydrogen - maybe.
- Comment on The Raspberry Pi 5 is no match for a tini-mini-micro PC 5 months ago:
I would add:
- if you wanted direct and low-latency access to cameras (for machine vision)
- Comment on Don't let people sell you flashlights :) 5 months ago:
It sure is.
A typical “obscenely bright” LED chip might be Cree XML, but many similar chips exist. Then you need a driver. Some are fixed while some adjustable with a tiny potentiometer. You’d need an 18650 cell holder (it can be made too, an 18650 will go into a leftover piece of 20 mm electrical cabling pipe with a spring-loaded metal cap engineered of something).
Myself, I bought a nice head lamp, but it broke after one year. The driver board failed. Being of the lazy variety, I replaced the board with a resistor to limit current and now it’s been working 3 years already. Not at peak luminosity, the resistor wasn’t optimal of course. :)
- Submitted 5 months ago to diy@slrpnk.net | 8 comments
- Comment on ZFS High Availability with Asynchronous Replication and zrep 5 months ago:
Thanks, that looks like something I might have to try. :) Myself, over the network, I still don’t do filesystem level incremental backups, sticking to either directories or virtual machine snapshots (both of which have their shortcomings).
- Comment on ZFS High Availability with Asynchronous Replication and zrep 6 months ago:
I’ve been hearing about ZFS and its beneficial features for years now, but mainstream Linux installers don’t seem to support it.
Out of curiosity - can anyone tell, what might be blocking them?
- Comment on Raspberry Pi 5 vs Intel N100 mini PC comparison - Features, Benchmarks, and Price 6 months ago:
From a person who builds robots, three notes:
- Camera
Raspberry Pi has two CSI (camera serial interface) connectors on board, which is a considerable advantage over having to deal with USB webcams. This matters if your industrial robot must see the work area faster, your competition robot must run circles around opposing robots, or more sadly - if your drone must fly to war. :( On Raspberry Pi, in laboratory conditions, you can access the camera (with big ifs and buts) at 500+ frames per second. That’s impossible over USB and unheard of to most USB camera makers.
- Optimized libraries
I know that Raspberry Pi has “WiringPi” (a fast C library for low level comms, helping abstract away difficult problems like hardware timing, DMA and interrupts) and Orange Pi recently got “WiringOP”. I don’t know of anything similar on a PC platform, so I believe that on NUC, you’d have to roll your own (a massive pain) or be limited to kilohertz GPIO access frequencies instead of megahertz.
- Antenna socket
Sadly, neither of them has a WiFi antenna socket. But the built-in WiFi cards are generally crappy too, so if you needed a considerable working area, you’d connect an external card with an external antenna anyway. Notably, some models of Orange Pi have an external antenna, and the Raspberry Pi Compute Module has one too.
- Comment on Fifty Things you can do with a Software Defined Radio 📻 8 months ago:
I’m inclined to add:
51: monitor the radio spectrum for drones (and if they are hostile, warn people about them) - there’s a DIY recipe for a monitoring station out there somewhere, and some Ukrainian guys scan their sky with HackRF
SDR is definitely a technology worth learning.
- Comment on What's Up? 9 months ago:
Trying to figure out how my heat pump supposedly supports WiFi… in unfathomable and non-standard ways. It’s available as an access point, I can associate and ping it, but no TCP ports listen and no UDP port responds. Nothing cool, undocumented features down to the rocky bottom. When you buy a heat pump and plan to automate its use, check out supported protocols before making a decision. :)
- Comment on Gravity Storage 101 Or Why Pumped Hydro Is The Only Remotely Real Gravity Storage 10 months ago:
Yep. As for why:
- the material being raised and lowered must be very cheap (to be able to afford much of it)
- the material must be possible to automatically handle in arbitrary amounts
- the friction of raising / lowering the material must be low
- the handling should not require a slope of particular grade or a specific height
Trains fail the cheapness and arbitrary amount check, along with the slope grade check. Sand fails the friction check. Concrete blocks are close to failing the cheapness and arbitrary amount check. Cranes fail the specific height check for certain ranges of height.
Water… it also requires a certain slope grade, but the range is not narrow.
- Comment on Scientist Discover How to Convert CO2 into Powder That Can Be Stored for Decades 10 months ago:
Looks sound, but I’m not qualified to say if success will follow:
en.wikipedia.org/wiki/Sodium_formate
Upon modest heating, sodium formate decomposes into hydrogen and sodium oxalate. Shipping that somewhere where it gets converted back to sodium formate is the tricky part, because that seems unlikely to happen onsite (on a small site, anyway).
- Comment on €45,000 for a heat pump installation in Germany -- really? 11 months ago:
Why does the title link point to a BBC story about South Africa? :)
To answer the question - I don’t know.
For comparison: installing an air-to-air heat pump for a tiny house in Estonia:
- heat pump unit (smallest unit, maybe 3 KW heat output for 1 KW electrical input), bought at the deepest discount: 450 €
- physical installation (mounting on a rack on a wall) - DIY, 0 €
- electrical installation (running a cable to the outer unit and back to the inner from there) - DIY, 0 €
- sealing and letting the working fluid into pipes - technician’s visit, 100 €
I would imagine that an air-to-water unit costs more (the cheapest are probably over 1000 €, unless you use a pool heat pump which can be crappy), that an average German family lives in a far bigger house (so maybe 3 x more wattage), and that they need 3 installation technicians for several hours (maybe 1500 €).
Beyond that - profit?
- Submitted 11 months ago to fixing@slrpnk.net | 1 comment
- Comment on Not All Batteries are Created Equal | Hackaday.io 11 months ago:
Unfortunately, yes.
I’ve had multipe experiences with seeing a flashlight battery which, according to labels, ought to have the capacity of an electric vehicle cell. And of course they don’t. :)
If one needs high current, measuring the current with a known and low resistance (e.g. car headlight bulb) helps.
- Comment on Solar module prices may drop 40% to $0.10/W by end 2024 11 months ago:
As an anecdote, I can tell that I’m still using my shattered solar panels. :)
(Normal people would not, of course.)
One broke during welding because a droplet of molten metal hit it - the hardened glass shattered all over. Another met with a flying plywood sheet during a storm - the plywood went right through with a corner and made a hole.
I use both panels on a wheelbarrow to pump water on the field during flood season. They’re perfect, nobody wants to steal them because they look like they got nuked. :D I worry about the wheelbarrow considerably more. :D
But yes, a recycling plan would be needed. Grinding them up and getting the aluminum back is not too hard, but how to separate the glass from the sealing silicone and doped silicon - I know some folks in Korea do it, but I don’t know how. :o
- Comment on Is there any use of an end-of-life LED lightbulb? 1 year ago:
If it were just a straight glass tube, there would be potential uses (heat collector), but due to the curvature (cannot be stacked) and presence of mercury, nope.
- Comment on Design of zinc bromide flow battery 1 year ago:
No experience on that front, sadly.
Compared to iron redox flow batteries, it has about 5 percentage points of more efficiency (75 vs. 70%), slightly better cell voltage (1.8 vs 1.2 V) and better energy density per electrode surface (0.2 W vs 0.05 W / cm2).
The “resetting” of cells seems like a nuisance. Quoting Wikipedia:
Every 1–4 cycles the terminals must be shorted across a low-impedance shunt while running the electrolyte pump, to fully remove zinc from battery plates.[3]
- Comment on Weekly What's Up? 1 year ago:
Still building a DIY tractor / excavator - racing against time, as autumn is rainy here and you cannot weld water.
It can already maneuver, turn the mast, raise the first linkage of the mast, lower / pull the second linkage of the mast, but the excavator bucket is incomplete and the bucket tilting mechanism missing.
The remote control system is also missing (relays on a slow boat from China), so currently I have to control it via cables. Limit switches are missing, currently it’s unsafe to use for a careless operator. Later on, it will be remote controlled and limit switches will ensure it cannot break itself.
My own reason to choose remote control is convenience (better ergonomics as I can write pre-programmed movements). If it works too well, I might send a recipe to a friend in Ukraine, with the suggestion of asking around - maybe someone needs cheaper mine disposal machines.
Hydraulic excavators are neat, but too expensive for me, and require far too much power.
- Comment on Fix leaking kettle 1 year ago:
I would recommend motor silicone, since it’s often rated for 300 C. The surface should be scratched or sanded for better adhesion. After it has fully cured (several days), one should probably do about ten “test boils” to flush out anything that might seep into water.
- Comment on 40GW of solar panels gathering dust in European warehouses 1 year ago:
I think the same.
In the country where I live, thare are regions where the grid doesn’t accept new production capacity - because installed capacity covers local demand and electricity cannot get where it’s needed.
Also, planning is slow and permits are issued slowly - I have an acquaintance who created a semi-legal solar park because waiting for permits would take too long. Electrically, everything is fine, professionals wrote the project and did the job. The parish just wasn’t informed, only the grid company was. Since it’s a small park, it flies under the radar. :o
- Comment on I built my first shed! So proud of myself! 1 year ago:
Looks very nice and practical. :) Congratulations.
- Comment on Turning CDs/DVDs into a solar panel 1 year ago:
Or a solar concentrator and a steam / Stirling motor.
- Comment on DIY Wheels for Bike or Trike or Trailer 1 year ago:
Interesting project. :) When clicking the link, I was expecting to see CNC aluminum plates, but rebar didn't cross my mind. :) Cheap, doesn't require a skilled welder or good tools, and since it's steel, fatigue is not such a big obstacle. Rust will be an issue, though (solvable with zinc).
