back to article Swede builds steam-powered Raspberry Pi. Nowhere to plug in micro-USB, then?

A Swedish schoolboy has built a miniature steam engine to power his Raspberry Pi. It is a piece of absolute engineering beauty. Forum user “Alexzpro”, posting in Swedish on the Svenska Elektronikforumet, put up a video he had made of the power plant for his Raspberry Pi. Alexzpro's generator is a small compound steam engine …

  1. Dan 55 Silver badge
    Thumb Up

    Not a bad design...

    ... I've seen power supply units which get hotter and give off more steam.

    1. This post has been deleted by its author

      1. Adrian Tawse

        Re: Not a bad design...

        Not only would a propper drive belt last longer it would be more efficient. The elastic band on the tension side stretches and on the opposite side contracts. The energy to stretch the band will be dissipated as heat in friction as the band passes over the spindle and absorbed into the elastic band as it passes over the flywheel. As a pure guestimate I would say that 30% of the energy is being wasted.

  2. pinkmouse

    "..Alexzpro's generator is a small compound steam engine... "

    Don't think so. A compound uses exhaust steam from a high pressure cylinder to drive a lower pressure one. This means the low pressure cylinder is bigger than the high, and both look the same to me.

    Now, some may say that they could be bored out to different diameters. True, but it looks like the exhaust runs from both cylinders, not just one as would be the case with a true compound.

    Oh, and it does look like a reversing gear to me too.

    al/ waiting for a pint...

    1. The First Dave Silver badge
      Boffin

      And from the footnote:

      "The regulator shuts once a small amount of hot steam has entered into the cylinder."

      No, it doesn't, the regulator is essentially just a tap, that restricts the flow-rate of the steam. The amount of steam that enters the cylinder is controlled by the valve-gear. In a simple model, it is probable that the cylinder (head) gets filled with steam at (almost) boiler-pressure.

    2. Adrian Tawse

      I agree, this is not a compound engine, it is just a dual cylinder engine. Neat though. I made a somewhat similar project when I was ten. My Grandfather gave we a model stationary steam engine. It was originally designed to run on coal but as such never quite raised enough steam to be interesting. My father had created, in his youth, a gas burner for it. This ran on coal gas and looked quite lethal. Not being able to get a supply of coal gas I designed an electric fan driven parafin burner. Actually more like a flame thrower,and quite lethal. You could drive a small generator from the engine. The generator produced just enough to power the fan. Flames would leap from every hole. My Mother screamed with fright while my Father laughed.

      My advice to any parent who wants their child to be an Engineer: build them a shed and don't ask too many questions. A few bunt fingers are a small price to pay for the pure joy of making something work.

  3. Anonymous Coward
    Anonymous Coward

    El Reg suspects his dad might have given him a hand... ®

    Seeing the 'hairy hand', I agree.

    Great fun though - I wish I still had my meccano stream engine from the 70's :(

    1. Anonymous Coward
      Anonymous Coward

      Re: El Reg suspects his dad might have given him a hand... ®

      "[...] wish I still had my meccano stream engine from the 70's"

      The standard was the Mamod steam engine with a little meths burner. Not sure why my parents bought me one - probably I pestered - none of my pals had one. Couldn't afford to buy any accessories - and for some reason I never used it to drive things with my No2 Meccano set. Over the years various mechanical projects made me wish I still had the latter with its beautiful brass gears.

      Somewhat surprisingly Mamod are still in business. Here's their steam pr0n catalogue.

      http://www.mamod.co.uk/shop-categories

      1. Anonymous Coward
        Anonymous Coward

        Re: El Reg suspects his dad might have given him a hand... ®

        The Internet is wonderful, sometimes.

        Here's the one I had:

        Steam Engine

        1. EastFinchleyite

          Re: El Reg suspects his dad might have given him a hand... ®

          That's the exact model that I still have (I'm 60 now). Still have the original box although fairly beaten up. I used mine for DC generation as well.

          My loft is a daunting place for memories.

          1. Neil Barnes Silver badge

            Re: El Reg suspects his dad might have given him a hand... ®

            I have a steam engine built as an apprentice piece by my godfather, around a hundred years ago... still works quite cheerfully on compressed air; even a good blow into the pipe is enough to start it.

      2. Steve Davies 3 Silver badge

        Re: El Reg suspects his dad might have given him a hand... ®

        Back in the 1960's I used a Mamod No 1 boiler to build a Gauge 1 Live Steamer. More like a 'Thomas' loco than anything running on BR but great fun. Ran it on the school track. Far too dangerous for todays softies though. What with all the risk assesments and H&S rules. Shame really.

        Gauge 1 is 10mm/foot scale for those who don't know.

        1. Bloakey1

          Re: El Reg suspects his dad might have given him a hand... ®

          <snip>

          " Far too dangerous for todays softies though. What with all the risk assesments and H&S rules. Shame really."

          <snip>

          True. I started up by buying radios and tvs at jumble sales, often they needed repairing. My parents often saw me launched across the room after having received a huge shock. They look on smiling thinking that i was a real card. They never tried to curb my dangerous pursuits and it formed me and made me the man I am today.

          Nowadays every special forces mission kicks off with a risk analysis and the health and safety officer is consulted. Seatbelts on toilets will be the next thing.

      3. werdsmith Silver badge

        Re: El Reg suspects his dad might have given him a hand... ®

        I still have my Mamod engine. It's a basic unregulated one with a hexamine burner and grease bearings. By dripping oil onto the bearing surfaces I could get it to run so fast it would shake itself apart.

        Those Stuart models look damn good!

      4. Putters

        Re: El Reg suspects his dad might have given him a hand... ®

        Still got the Mamod engine in the loft - decidedly used, but still in (most of) it's box. An early enough one to have the meths trough and not the solid fuel blocks.

        For some reason my grandad decided that it was an ideal present for a 3 year old boy ...

        1. W4YBO

          Re: El Reg suspects his dad might have given him a hand... ®

          "For some reason my grandad decided that it was an ideal present for a 3 year old boy ..."

          Look where you are now. Smart grandad!

    2. Adrian Tawse

      Re: El Reg suspects his dad might have given him a hand... ®

      Absolute rubbish. How dare you denigrate the lad.

  4. Known Hero

    Fun project

    I really do admire what people can do :)*

    *other times I'm quite horrified !!

    1. swampdog

      Re: Fun project

      "I really do admire what people can do :)* *other times I'm quite horrified !!"

      Tickle a shrimp.

      1. Known Hero
        Paris Hilton

        Re: Fun project

        Ìs that a suggestion or a warning not to google or do?

  5. Lee D Silver badge
    Happy

    Call me when he gets it working from a clockwork mechanism..

  6. lnLog

    Stuart engine?

    Looks like a STUART D10 engine http://www.stuartmodels.com/

    1. Anonymous Coward
      Anonymous Coward

      Re: Stuart engine?

      Yes, at 42-44 seconds you can clearly see the "S" logo on the side.

      However the report:

      "A Swedish schoolboy has built a miniature steam engine"

      is rather more impressive than:

      "A Swedish schoolboy has bought a miniature steam engine"

      1. Steve Davies 3 Silver badge

        Re: Stuart engine?

        He could have bought a set of castings for the D10 £160.00 from Stuart.

  7. Velv Silver badge
    Coat

    Steam Radio

    Is the Pi running an Internet Radio Streaming app? Or should that be steaming app?

  8. ZanzibarRastapopulous

    Voltage Drop

    Bigger flywheel?

    1. G R Goslin

      Re: Voltage Drop

      Ah, Stuart Turner. Will we ever see their like again

      This motor actually does come with a larger flywheel. The one fitted is for use in a boat (more compact)

    2. Bob H

      Re: Voltage Drop

      Bigger capacitor?

    3. Stoneshop Silver badge
      Boffin

      Re: Voltage Drop

      He's using a linear regulator (plain 7805), which, apart from simply dissipating the voltage difference as heat, has a current limit of one amp. Which is just a tad low for booting a Pi, and some extra capacitors won't help you there.

      On the forum they're talking about him having to fit a switching regulator instead.

      1. Anonymous Coward
        Anonymous Coward

        Re: Voltage Drop

        "On the forum they're talking about him having to fit a switching regulator instead"

        The "buck" down converters are very cheap from the Far East - about £2. The standard module accepts up to 35 volts DC and you can adjust the output right down to a couple of volts. Max current about 2amps.

        They also sell "buck" up converters. The one I bought had an output capacitor marked as 35v - and it exploded during initial adjustments while I was trying to get a reading on the meter. Others advertised with the same nominal max 35 volt output had a 50v capacitor - which seems more sensible.

        1. TRT Silver badge

          Re: Voltage Drop

          I'd watch those buck-boost modules. As the supply voltage drops, the current draw rockets up. Most of the circuits I've seen don't have any current limiting on the input.

        2. The First Dave Silver badge

          Re: Voltage Drop

          The rule of thumb I was taught was that caps should be rated at at least twice the actual voltage, so even 50v is a bit low for a 35v circuit.

    4. Jan 0
      Boffin

      Re: Voltage Drop

      From the article:

      > the Pi's greater demand for juice when it boots causes a voltage drop big enough to force the mini computer to reboot.

      I'm amazed that such a small steam engine can produce enough power to run a minicomputer as well as a microcomputer. Is the minicomputer lurking in his dad's attic?

      1. Stoneshop Silver badge

        Re: Voltage Drop

        I'm amazed that such a small steam engine can produce enough power to run a minicomputer as well as a microcomputer.

        I can't readily find actual power output numbers for the D10, but doing a bit of arithmetic with dimensions and data for other models, I end up with 300..400W at the crank*. With a suitable generator and voltage regulating gear you might indeed be able to run a last-generation '11 CPU with a bit of memory and a modern** disk.

        It won't be a fully kitted-out /70 with a bunch of RM05s and a TS11.

        * But as I'm not a steam engine surgeon, this could be totally off.

        ** SATA interfaces vividly remind me of SDA.

  9. Kubla Cant Silver badge

    Loop much?

    the Pi's greater demand for juice when it boots causes a voltage drop big enough to force the mini computer to reboot

    I assume "the mini computer" refers to the Pi*. So what you're saying is that the Pi's demand for juice when it boots causes it to reboot. Whereupon its demand for juice causes it to reboot.

    I'll have to stop there, as I can't stand typing "demand for juice" any more.

    * Unless there's a PDP-11 or the like in the setup, which rather detracts from its simplicity.

    1. captain veg

      Re: Loop much?

      > Unless there's a PDP-11 or the like in the setup

      Could use an x64 server, and power the steam boiler from the waste heat.

      -A.

      1. Bob H

        Re: Loop much?

        A sterling engine?

    2. J.G.Harston Silver badge

      Re: Loop much?

      "Unless there's a PDP-11 or the like in the setup"

      There might be. :)

      Admittedly, that's a screenshot from a Xilinx Spartan FPGA but it's currently being ported over to the Pi.

  10. Chris 103
    Joke

    Unbelievable...

    There was me thinking Sweden was a nation of Eco warriors out to save the world, and now I find they are encouraging their children to build hydro-carbon powered generators.

    1. TRT Silver badge

      Re: Unbelievable...

      "I've noted your comment and instead of using a hydro-carbon source, I've adapted the engine so that it runs of geothermal energy instead. With the assistance of my father, I've bored a hole through the floor of the school gymnasium, through several layers of topsoil, alluvial deposits and bedrock until the shaft is sitting just above an active lava tube that I identified through a series of seismic surveys."

      "And that provides the heat to power the engine?"

      "Good lord, no! The temperature at the termination of the bore site it a mere 90°C. No. We need far more heat energy than that. The bore hole is where I'm going to ram this small thermo nuclear charge in order to crack open the Earth's crust and reactivate the dormant volcano about three miles to the south of the town... the resultant volcanic eruption will provide enough energy to boot the computer and we should hear it auto-playing Für elise through the midi-emulator for about 20-30 minutes. Before we all die of sulphurous gas emissions, and ash suffocation."

    2. PickledAardvark

      Re: Unbelievable...

      The propane gas burners used to heat the boiler would have been test appliances.

      A true Scandinavian would have cut down a few trees (sustainable resource) for a wood gas generator to power his car to go shopping and experimented with a turbine.

  11. GlenP Silver badge

    Thinks...

    I've got a couple of small Stirling heat engines at home, trouble is the larger one refuses to run and I doubt the smaller toy one would generate enough power.

    Those could definitely run of the waste heat from an x64 server!

  12. Old Used Programmer

    Probably the simplest way to solve his power surge problem would be a large capacitor...and a bleed resistor to take the charge off when the system is shut down.

    1. Stoneshop Silver badge
      FAIL

      Nope

      He's using too small a regulator. The generator is capable of delivering 17V at 1A, so 17W, but he's using a 7805 linear regulator with a current-limited output. A larger capacitor won't help; a switching regulator would be able to convert 17V @ 1A to 5V @ 3A, which would run the Pi without dropping out.

      And a bleed resistor for a low-voltage buffer? Total overkill.

      1. Mage Silver badge

        Re: Nope

        I'd use an AC motor not DC. No brushes to wear out.

        SMPSU is what is needed.

        1. oldcoder

          Re: Nope

          Not sure that would work as a generator.

          Most AC motors don't have built-in magnets, depending on the

          external power to generate the rotating magnetic field... and that induces current in the armature which then reacts to the field.

          1. Stoneshop Silver badge
            Boffin

            Re: Nope

            Bicycle dynamos perform just fine, generating AC without an exciter coil. Most motorcycle dynamos also have a permanent magnet with a stationary coil; only Bosch-type generators use an exciter coil for which you theoretically need the battery to have some charge to bootstrap the process (but often the rotor tends to have enough permanent magnetism to do so even without a battery).

            Generators with an exciter coil are easier to regulate to a particular output voltage even with a simple mechanical voltage regulator. For a dynamo you'd need a hefty zener or robust stuff that shorts the output.

  13. VeganVegan

    Steampunk!

    See title

  14. Stevie Silver badge

    Bah!

    It's no wonder my video games won't load properly if the voltage is dropping every time they boot up the STEAM server.

  15. Mark M.

    Steam engines and "steampunked" computers.

    If he was going to build a steam engine to power a computer, he should have built a Babbage engine to go with it.

  16. Anonymous Coward
    Anonymous Coward

    Revering gear.

    "Oh, and it does look like a reversing gear to me too."

    There are expansion links at both ends of the engine but the operating handle for them is on the right hand end.

  17. John Brown (no body) Silver badge

    I run my whole house off steam

    Most of my electrickery comes from Ferrybridge and like most power generation in the UK, is generated via steam turbines heated from gas, coal and nuclear.

    Good on the lad though. I bet he had fun doing it :-)

  18. MaddMatt

    Steamnote...

    I think the steamnote is a little incorrect.

    The regulator is a throttle, you open and close it to control engine speed overall.

    The description in the steam note relates to the Valves, opening for a short time, determined on some engines by a variable cutoff adjustment (e.g. a great big lever on a steam locomotive).

    This then allows the steam to expand, expending its energy pushing down the piston.

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