back to article Ten pi-fect projects for your new Raspberry Pi

There was an article a while back, in Scientific American I think, that posed the question: given a super-powerful computer, with infinite computing power shoe-horned into a coke can, what would you do with it?* The arrival of the Raspberry Pi (RPi) prompted a similar sort of question: given an (almost) disposable PC with late …

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  1. ukgnome
    Thumb Up

    Pi-BX looks like a great little project.

    My only obstacles to little projects are wife based.

    1. NickNightingale
      Go

      Wife acceptable

      I have set up RasPBX on a Pi at home. I initially used the SPA3102 but could not get rid of the echo so I changed to an OBi110 which at about 35GBP is cheaper and much better. Now voicemails are attached to e-mails instead of hiding behind 1571, we can divert international calls straight to voicemail (as they are pretty much all nuisance sales calls) and with an additional Sipgate trunk and some Zopier soft phones we can have multiple simultaneous phone calls. Amazing for a little toy computer.

      1. Return To Sender
        Thumb Up

        Re: Wife acceptable

        That answers a question I was going ask - the OBi110 with RasPBX. I have a, errmm, window of opportunity to muck around with this (couple of knackered DECT phones in the house). 35 quid for the OBi rather than 56 for the Cisco (on amazon at least) makes it easier to put the cost case to the CFO (wife...). Have an upvote, squire.

      2. B_K

        Re: Wife acceptable

        Running RasPBX here was well, though I managed to sort the echo out on the SPA3102 after some tweaking. Voicemails getting emailed, black lists, natty menuing system to filter blocked callers. No more junk calls!

        Same Pi runs as an AirPrint/Cups server, and MRTG monitoring bandwidth, just for the heck of it.

        I now need to buy at least one more Pi, probably two.

        Also looking at the options to use them for exhibits at the local Aviation Museum (someone sits in a fighter jet, Pi senses it and plays audio, video etc)

      3. Osmosis Jones
        Thumb Up

        Re: Wife acceptable

        I have always wanted to be able to set-up a caller-id for my landline that spits out the info to a local device which then turns it into a remotely accessible html page. Could I do this cheaply with a RasPBX similar to your setup? If so would love to pick your brains.

  2. Anonymous Coward
    Anonymous Coward

    My project...

    At the moment, I'm working on a rPI intelligent thermostat. The rPI is going to be attached to the wall next to the boiler and will handle the mains switching to switch the boiler on and off.

    The thermostat itself is an Arduino with an LCD display, telling you the temp and when it's next going to switch on, also the target temp. The temperature sensing is done with an LM35 temperature sensor, at the moment it's all hooked up with USB/Serial ports (and not to the boiler, yet) but will use xbee.

    The rPi runs a mysql database and the system as a whole will allow rules based heating configured from web or the thermostat, such as:

    On for an hour, on all day, off for a week, minimum house temperature (frost protection), daily scheduling etc. I'll be storing all the temperatures in a database and hoping to use this more intelligently in future...

    1. David Pollard

      Re: My project...

      This sounds neat.

      In systems which have stored hot water it's possible to use two pumps and relay switching rather than the usual 3-port valve which tends to be prone to failure. The cost of an extra pump is similar to the cost of the valve, though non-return valves have to be included in each circuit and fairly careful design is needed to avoid unwanted thermal syphoning between the two loops when only one is in use.

    2. Tom Sparrow
      Mushroom

      Doing similar

      Have a spare wireless thermostat/receiver that I'm cannibalising for actual switching. The transmitter is simple 3v pulse signal to an on or off pin (the actualy upload codez are all on the little daughter board thankfully).

      USB thermometer currently in the post (£8 / ebay) and than it's all software - I'm hoping to persuade it to look up the outside temp & wind chill from the met office then reference a schedule of when the church hall is in use and calculate when to turn the heating on so it's suitably warm when needed. In winter, that can be 3am some weeks, despite having a boiler the size and power of the flying scotsman (probably about as efficient, too).

      Thermonuclear boiler might be a suitable replacement, hence icon.

      1. Anonymous Coward
        Anonymous Coward

        Re: Doing similar

        WRT Outside temperature - This is something that I'm going to be looking at, once the first stuff is in and running (my partner keeps on at me about "feature creep") but I'll be putting a sensor on the North side of the house, which should pick up temperature falls, you can then do pre-emptive heating which actually saves you a few hundred quid a year in gas.

        What I didn't think is that I live pretty close to a Met Office site and a University where they have a weather station, also used by the Met Office, so all are probably online - it may well be worth looking to see if these are useable, and doing it in software rather than bodging together something else electronicy. That's got me thinking...

    3. Suricou Raven

      Re: My project...

      Switch to a one-wire bus with the DS18S20 temperature sensors and you'll be able to hook a lot of sensors up to it - I used to have them all over the top floor of my house, poking through holes in the ceiling with the bus in the loft. That way your thermostat can more inteligently decide when the heat is needed, and analysing the sensor logs will tell you which rooms are losing the most heat to the outside world.

      1. Anonymous Coward
        Anonymous Coward

        Re: My project...

        I have been thinking about how to measure the temperature in all the rooms, I suspect that this will come under "feature creep", and I have been looking for an excuse to have a look at one-wire... The problem that I have is the house is a victorian terrace and it's not particularly easy to run cabling round the place, unseen at least.

        I'd like to get motorised TRVs, so that individual radiators can be turned on and off automatically. This way, if I'm working from home, the office can be warm and the rest of the house at a minimal temperature. I'm not sure if these even exist though...

        1. Tom Sparrow
          Go

          Re: My project...

          Motorised TRV's definately exist - we got them put in at work initially from Honeywell (not my project) - £80 per valve and £150 for the control panel to set the target temperature (on a schedule).

          When I did my heating at home recently I looked for something a little more sensible in price - Pegler make a TRV that is motorised/scheduled target temperature changes all in one for around £25. Each room is now turned up and down to a schedule as necessary (i.e. kids rooms off while they're at school, dining room turns right down in the evening & our bedroom doesn't start warming up until 9 or 10). They can be adjusted manually at any point, and revert to programmed temp at the next scheduled change.

          There's a USB programming stick and remote available (600MHz). The programming only has s/w for windows at the moment, but it's just a USB/Serial interface from what I can tell so that's a project for later on.

          1. Tom Sparrow

            Re: My project...

            See here http://www.saveonheatingbills.co.uk/ for details.

        2. Nigel 11

          Re: My project...

          Victorian terrace should be easy! It has floorboards? You can push your low-voltage low-bandwidth wiring into the cracks between the boards in ine direction, and pull wires through the space between the joists under the floorboards in the other. Modern flat with a solid concrete floor is harder, though if you have carpet you can also easily put wiring under the carpet.

          Very thin copper wire or tape attached to a wall, wallpaper-glued down with tissue paper and painted over would probably also work. I once attached a multi-element FM antenna to a ceiling that way (antenna made of aluminium foil, then papered over and painted). Worked a lot better than a dangly wire, and a lot cheaper than getting a man to attach a proper antenna to the chimney. The room needed painting anyway.

          Or with RPi at £30 ... go wireless?

    4. cantankerousblogger
      Stop

      Re: My project...

      Sounds really interesting, and I don't want to be a spoil-sport, but it might be a lot easier and better to use the programmable Danfoss Eco Living TRVs available for about £35 from say Plumbnation or elsewhere:

      http://www.screwfix.com/p/danfoss-living-eco-trv-sensor-head/91907

      Then you'll have a thermostatically-controlled TRV, with a fully programmable seven day timer and local manual override, in every room. In our five-bedroom Victorian house, the variation in room warmth and use is such that a single thermostat and control in the hall (or wherever) isn't much use. I've even set up the controller in our dining room to heat up the room for my daughter's piano lesson on a Saturday morning after she complained it was cold. The controller is also beautifully intelligent, so if you say you want the room at say 21 degrees at 6 a.m. it learns continuously what time it needs to switch on to achieve its objective.

      Buy the Danfoss valves and fit and programme in half an hour for each radiator (the TRVs aren't too noisy either and don't lose their programming when you change the battery like some others - beware) and build a lovely MAME games table instead, which looks seriously cool.

    5. Sport Monkey
      Thumb Up

      Re: My project...

      If you store temperature data, on and off times (and external temperature) then calculate the cooling curve you can probably save a good amount on gas consumption. Especially if you had a daily heat pattern (i.e. cold overnight) not just on/off etc.. It's a nice project, if you can build some intelligent software it would be great, especially if you're able to use a web server for remote control (or SOAP).

  3. hammarbtyp

    Photo viewer

    My most likely project would be a photo/video frame. Stuff you 10" digital photo frame. 14 inch LCD+one Pi and you should have a digital frame worthy of your content. Plus if you add wifi you will be able to easily access new content as well

    1. Arthur 1
      Unhappy

      Re: Photo viewer

      The big problem with any project along these lines is that you'll have to use a complete monitor rather than just being able to use the bare LCD. Adds a lot of bulk and inefficiency to the whole mess.

      The DSI on the Raspberry Pi might as well not be there, there's no way to configure it, all the drivers are closed/proprietary/embedded in the GPU with no public documentation or toolchain available. Afaik, nobody's managed to actually hook an LCD up to it in any reasonable way. I really wish they'd fix this mess, because there are so many cool projects you could do with the added bit of size reduction.

  4. JDX Gold badge

    KindleBerry

    I don't really see the point of this one. Can you really not buy a small portable LCD screen for the same cost as a Kindle, hell you can get a complete Android tablet for under £100 in the first place. I get the point is fun over function but this seems one step too far.

  5. g e
    Go

    Not to mention a WiFi Access Point

    If a LAMP server qualifies then this easily does!

    www.pi-point.co.uk

  6. Andus McCoatover
    Windows

    My most dificult RPi project at the moment...

    ..is to get the SD card to stay in the frikking socket! Returned under warranty, replacement exactly as bad!

    Already had to take a file to the RS-supplied case, having noticed the case's dimensions seem to have followed my ex-manager's engineering principle:

    "Measure it with a micrometer, mark it in chalk, then hew it out with a blunt axe".

    Bloody case looked on arrival like it's been chewed by rats!

    (Then, it'll become my webserver).

    1. Anonymous Coward
      Thumb Down

      Re: My most dificult RPi project at the moment...

      "..is to get the SD card to stay in the frikking socket! Returned under warranty, replacement exactly as bad!"

      You returned it because the card fell out? I have to say that doesn't seem to be in the Spirit of Pi (tm). What's wrong with a bit of electrical tape, blu tac, or for a more-permanent-than-time-itself solution, a dab of silicone mastic?

      1. Andus McCoatover
        Windows

        More like the "Zen of Pi"

        No, Leswinger, the card wouln't stay in. Furthermore, the tiny bits of gold (as a switch), to detect whether a card was connected or not were buckled. (I guess I could've just somehow twisted the two together, but I couldn't find my glasses.....

        When I've got money, I'll fire the bugger up with 16G card. THEN, i'll persuade the bugger with 16 Gig up its jaksy! That'll make its eyes water!

        (That's the problem. I wanna change the card. Duct-tape, etc OK once I get the thing to boot, I'll use a memory stick. Until then however...)

        1. pPPPP

          Re: More like the "Zen of Pi"

          I use a Transcend 32 GB Class 10 SDHC card. Works a treat and performs well. Has never fallen out.

      2. Andus McCoatover
        Windows

        Re: My most dificult RPi project at the moment...

        @Ledswinger:

        Bad as that. Put card into socket without case, card dropped straight out - vertically, not horizontally. So used a bit of tape, placed it in case. Micro-usb and HDMI sockets obscured by the case itself. Oh, and without a lot of cutting and filing of the SD hole, because it wouldn't sit in the case. Frick it, either it goes back to RS, or I buy and load a 32 gig. card, araldite it into position, drill the case to buggery, thus voiding any warranty I'd hoped for. Or, I solder in a better-quality holder. Warranty void again.I want to be able to change the SD, as-an-when I need to (they don't last forever). Now, again, extra time and expense to return it, and wait another month...Serious e-mail to RS going out today.

    2. Chris King

      21st-century RAM Pack Wobble ?

      I didn't like the idea of the SD card sticking out of the case, so I bought a pIO adaptor from ModMyPi and used a MicroSD card instead:

      https://www.modmypi.com/sd-cards-and-adaptors/raspberry-pi-micro-sd-card-adaptor

      This doesn't stick out of the case, but you have to open the case up to change the card.

      1. Andus McCoatover
        Windows

        Re: 21st-century RAM Pack Wobble ?

        Problem is, if you look at your photo, the left-hand 'cheek' to hold the card in, on both (same one?) is completely missing. Hence, the card simply fell out.

        I'll post photos to RS staff.

    3. Stevie

      Re: My most dificult RPi project at the moment...

      Sparkfun sell something they call the Pi Tin. I used it on four machines so far with no problems. Snap fit, securely closed yet easy to open if needed.

      Only problem if you can call it that is that there is no blanking plug for the GPIO access port.

      Cheapest case I've found, too. It would cost me more than $7 to build one from Lego.

      1. FrankAlphaXII

        Re: My most dificult RPi project at the moment...

        Just cut a port into the case for the GPIO, or use a drill and drill it. Im sure it would work.

  7. xranby
    Boffin

    Build a Raspberry Pi internet controlled rover.

    Build your own Raspberry Pi rover: http://www.homofaciens.de/technics-robots-R3-construction_en_navion.htm

    Watch the introduction video http://www.youtube.com/watch?v=tzfjiD4UI9g this will enable you to become a member of the IRDA, Interplanetary Rover Driver Association, then proceed to operate rovers operating inside distant universe. R3 control center on planet earth for the Curiosity Pi rover: http://www.homofaciens.de/technics-robots-R3-control_en_navion.htm

    Earth needs more rovers!

  8. Suricou Raven

    Cloud storage.

    Having a handy webserver you can upload files to from a browser and download from again is a good idea. I set one up myself. Not using a Pi - it runs on my home server/router. Just apache, some .htaccess files and one rather small perl script. You really need very little to make it work.

  9. Anonymous Coward
    Anonymous Coward

    Digital Signage

    I'm looking at speccing up some RPi units to run digital signage setups. You can get a 32" HD TV for not a lot these days and a wifi-connected RPi with Screenly seems just the job.

  10. Russ Tarbox
    WTF?

    How is that "netbook" running Windows?

    Unless it's an RDP session or similar...

    1. Chemist

      Re: How is that "netbook" running Windows?

      What netbook ?

    2. Annihilator
      Boffin

      Re: How is that "netbook" running Windows?

      Short answer - it's not!

      http://www.instructables.com/files/orig/FXN/P9DX/H8RVBCHF/FXNP9DXH8RVBCHF.jpg for the full size image that shows the desktop more clearly. It's the Wheezy distro by the looks of it.

      1. Chemist

        Re: How is that "netbook" running Windows?

        That's, in fact, why I asked my question above as I couldn't see anything running Windows.

  11. Mage Silver badge
    Coat

    Is that it?

    Really the top 10 projects El Reg can find?

    Hmmmm...

    Mines the one with 20 Bernard Bambini Pi Projects.

    1. Anonymous Coward
      Anonymous Coward

      Re: Is that it?

      Don't let the door hit you on the way out.

    2. Jason Bloomberg Silver badge
      FAIL

      Re: Is that it?

      It is quite weak isn't it; no more than you will find people doing with other hacked together PC boards. There are advantages to the Pi - low power, compact footprint - but it is sometimes hard to see how it's really any better than a second hand laptop or PC costing £5 for the projects built around it.

      What would be nice to see are projects which could not be done except with a Pi. Projects where the Pi brings something to the table, rather than just being a smaller version than how it would have been done before. There must be wearable projects it is being used in, applications for aiding disabilities, and things like that, something interesting, unusual, exciting, but all we seem to see are reinventions of the past.

      The Kindle as a display is more a Kindle project than anything else. PC in a table, PC as a server, PC in a suitcase, PC connects to projector, PC connects to weather station, PC as another server wearing a "cloud" badge, PC connects to load sensors, PC running Asterisk. Yawn. Replace PC with Pi and it's still yawn.

      Coming soon; bleeding edge experimenter connects keyboard, mouse and monitor to Pi to create a working computer.

      1. James Hughes 1

        Re: Is that it? @Jason

        I get the impression you are a glass half empty type of guy. If you had spent more than 3 seconds thinking about this, you would have realised that these are just some of the projects you can do. It's not an exhaustive list! Yes, you probably could do some of them using a cheap PC, but GPIO would be a problem, as would power consumption and size.

        I suggest Google, and some thought.

        1. JEDIDIAH
          Linux

          Re: Is that it? @Jason

          PCs are typically small or cheap but not both. The PI takes both to a new level. It's like an AppleTV or Roku in this regard. You can try to make PCs smaller but then you end up with a $1000 Steam Box or a Mac Mini. It's also nice that the PI achieves it's cheapness without being some ancient thing you retrieved from a dumpster.

          Who wants their cool project to fail because it's made of parts that finally decided to die of old age?

          1. Mark .

            Re: Is that it? @Jason

            "You can try to make PCs smaller but then you end up with a $1000 Steam Box or a Mac Mini."

            Though note that MicroATX form boards are commonplace, and there are plenty of small-size PC boxes. Not that I disagree with the gist of your post - in particular, these weren't around (or at least, not common) in the 1990s, so any £5 PC he finds from that era is going to be big. But there's a lot more choice than those two options.

            Most people don't need a dedicated graphics card these days, meaning the days of PC cards are gone, similarly one can do away with the DVD drives.

            1. pPPPP

              Re: Is that it? @Jason

              I have a collection of old PCs in the loft and I use them mostly as a dumping ground. I often thought about leaving one on so I could connect to it remotely but could never justify it down to the cost of the electricity (even though it's not a huge amount) and the fact that I can hear the fans when I'm lying in bed.

              The Pi has allowed me to do just this. It has a couple of 2.5" external drives connected, giving me 1.5 TB of storage, and I can always wake the others with a magic packet if I need to. I've got one port open to the outside world which is for openvpn, so I can usually only get in from my laptop, although I've set a friend's PC up to connect automatically too, so I can log on there to help him out (he's not a techie). His files are also backed up on the Pi.

              I have an ftp server too, which I enable if I need to and it also has qbittorrent so I can download torrents when I want, wherever I am in the world.

              The drives sit idle most of the time, as does the CPU. It's silent and consumes hardly any power. In short, it does exactly what I wanted my PCs to do, and it takes up very little space. I can't bring myself to throw the PCs out because I'm an electronics hoarder, and it's useful to have native i386/amd64 boxes every now and again. I wouldn't buy an old PC to do the job though. Not when the Pi is so cheap.

              The marketing guys would call this set-up a cloud probably.

      2. Mark .

        Re: Is that it?

        "but it is sometimes hard to see how it's really any better than a second hand laptop or PC costing £5"

        Honest question - how easy it is to get such a £5 PC? Typically second hand PC prices tend to have a lower limit that's much higher than that, even if they don't seem worth it. And anything worth less than that is likely to be thrown out, so it's a matter of luck as to whether you know someone with some old hardware to give away. Admittedly Freecycle may help - but I can see the point that, just because a 1990s PC ought to cost £5, doesn't mean I can easily get hold of one, when most of them are now lost, collecting dust, faulty or thrown out.

  12. Anonymous Coward
    Anonymous Coward

    PIANA

    The Raspberry Pi Synthesizer - http://raspberrypisynthesizer.blogspot.co.uk

  13. Rol

    Is this workable?

    A cheap web cam placed to capture visitors at the door, along with a similarly cheap microphone to capture the conversation all activated by the user pushing a button as they answer the door to a stranger. or even automated to recognise the door bell / knock.

    The image and sound uploaded to a dedicated site where volunteers can quickly assess the situation and call the police if necessary to avoid another £5000 roof tile / spare tarmac / give us all your savings scam.

    Or voip to a concerned relatives mobile where with the addition of a speaker to the system could talk directly to the "salesman" proffering some useful if not flowery advice.

    I think the RPi would handle this and therefore bring the whole system in well under £100, which is nothing compared to the peace of mind it provides, then again I would bow to the wisdom of those here, who unlike me, are already engaging with this remarkable device.

    1. pPPPP

      Re: Is this workable?

      Be careful with this. One issue they have had with the Pi is USB compatibility. My external drives used to be problematic but they fixed that with a firmware update. The cheapo USB camera I bought still has issues though.

      There are some cams that do work, and they are working on the USB issues. Just bear it in mind.

  14. Nigel 11

    Rural networking

    Fairly challenging, but a case of open-source development once, fix hundreds of thousands of people's problem.

    It ought to be possible to connect an Rpi, a solar panel, a battery, a weatherproof box, a USB hub, some USB wireless thingies and some directional antennae, to make a goes-anywhere wireless access point. Stick that on a pole in a field somewhere, with line of sight to another pole, and another, and another ... chain them together from a location that can get broadband, to a village or hamlet that can't.

    Software that auto-assembles a network, so apart from configuring the broadband end the future problem abounts to errecting poles, screwing a box onto the top, and pointing the antennae in appropriate directions.

    It's a cheap somewhat limited implementation of something that the military are playing with for battlefield communications, and disaster relief agencies for getting communications up again after a natural disaster.

    1. Anonymous Coward
      Anonymous Coward

      Re: Rural networking

      Didn't The Reg's Billy Ray already have that idea, what with his trestle-on-the-roof radio link?

      1. Nigel 11

        Re: Rural networking

        It's not a new idea at all. Years ago I read about the installation of a working telephone booth at the Burning Man festival, using a chain of off-the-shelf routers strung across the Nevada desert. It's just that it's getting more affordable, and the RPi lets you integrate things like battery and power management to a greater degree. There are also quite a few routers that one can "jail-break" and convert into small fully programmable Linux boxes. (OpenWRT, etc.)

        A related idea would be just to use a pair of solar-powered RPIs (or OpenWRT boxes) to wirelessly bridge a road. This is useful, because while you might persuade a few landowners to let you string a fibre across their land, just try getting permission to take a fibre over or even under a public highway. So, don't try. Just put a solar-powered fibre-to-wireless router on each side. You wouldn't even need directional antennae (which may not be entirely legal).

        1. Nigel 11

          Regime change, anyone?

          Same idea as rural networking, but a different application, for brave people living under repressive regimes. Build your own hidden communications network.

          This more or less happened in Libya, although the rebels "stole" the existing wireless network infrastructure rather than just installing their own.

    2. Vic

      Re: Rural networking

      > chain them together from a location that can get broadband, to a village or hamlet that can't.

      It's not a difficult technical problem, as long as you get enough PV panels to power your backhaul (whatever you use to link the units together).

      But now you find someone doing something nefarious on the network. Guess who gets the knock on the door...

      Vic.

      1. Nigel 11

        Re: Rural networking

        Knock on the door of whoever is paying for the broadband, of course. I'd suggest that would be the "Borchester Village Internet Co-op" or suchlike. Obviously take appropriate software precautions so that only authorized users get access (such as end-to-end as an encrypted pipe, and some logging of who and when).

        Not really any different to any other smallish not-for-profit's set-up, apart from the wireless pipe to the broadband connection location.

  15. Mister_C
    Boffin

    Solar moitor

    Starting to look at reading the solar panels' output and varying the immersion heater to use free juice when the sun shines rather than 3kW when the water wants it. Then there's play / pause on the dishwasher so the magic cupboard works while I do (at the moment most likely using an xBee linked solenoid to poke the buttons directly). Oh, and switching on the charger for the laptop batteries through the day for evening browsing...

    1. handle

      Re: Solar moitor

      I've looked at driving an immersion heater from solar panels too. The awkward thing is doing it legally. If you use phase angle control you need major filtering, and if you use burst firing (which works because of "elasticity" in the electricity meter) then you are likely to break "flicker regulations". If you don't bother, you can at least feel better that your panels are offsetting electricity rather than (presumably) gas use.

      As for charging laptop batteries, the extra strain on them would probably cost more in replacements than the reduction in your electricity bill. It's annoying!

      1. Nigel 11

        Re: Solar moitor

        I must have missed something. If you want to heat water from solar PV electricity, don't you just put a 12V or 24V immersion heater in your tank and connect the raw DC solar panel output to the heater?

        I would have thought that the rest involves a motorized switch to connect the panels to the inverter or to the water tank as desired. If inverters are allergic to being completely disconnected from their PV panels at short notice, you could switch between all the PV output going to the inverter, and the PV output going to the inverter and the water-heater in parallel.

        And if you also want to be able to heat water from mains electricity, just put a second immersion heater in the tank. OK, it may be hard to source a tank with two bastard curcular cut-outs at the top for screwing your immersion heaters into. I find that struggling with one is quite enough!

        Back to the original idea, surely there's such enormous thermal inertia in a water tank that you wouldn't have to switch the heater on and off more than once every few minutes. Flicker regulations?

        1. handle

          Re: Solar moitor

          @Nigel 11: Yes you have missed quite a few things.

          - Strings of series-connected solar panels as used in domestic PV installations produce up to a few hundred volts

          - If you want to get the maximum power out of themuse them efficiently you don't just slap on a constant resistance load, you have to track their maximum power point with a varying impedance, which is one of the functions of the inverter

          - It is very problematic to switch high voltage high current DC because you draw arcs which are not extinguished every half cycle. There are dire warnings on inverters to isolate them by switching off their AC outputs before the isolators on the inputs. You'd have to stop the inverter before removing its input - and what about when you come to switch out the immersion heater?

          - The inverter takes a considerable time to start feeding into the grid when its input goes above threshold. This is because of the self-diagnostics it runs for safety (anti-islanding, i.e. not allowing power out if the grid is disconnected; earth fault detection as some models do not isolate panels from the mains for efficiency)

          - The generation meter is on the output of the inverter; if you intercept the panels you don't get paid for what is generated

          - There is a source of varying power (the panels) and a load of varying power (the property) - to use the difference optimally requires proportional control of the heater, not a crude switch

          Despite all the electron mangling it has to do, my inverter claims an efficiency of around 95%, and with its fanless heatsink it doesn't melt in full sun, so I can believe it.

          I came to the conclusion that the amount of money you save is quite modest, for a lot of effort. It's a great hobby project but not a cash cow.

        2. YetAnotherLocksmith Silver badge
          Mushroom

          Re: Solar monitor

          Surely the easy way to do that is to simply run a wire from the panel inverter output to the input terminals of your water tank's immersion heater, then add a relay so that when it switches the solar in the mains disconnects? And vice versa.

          A zero-crossing electronic relay will last far longer under a 3kW load, and be nicer to your electronics on the other end.

          Obviously you'll need to run some temperature feedback too, so you don't run the risk of too high a tank temperature if the UK sun ever stays out for more than 35 minutes if the heater itself doesn't manage that. Otherwise, see icon.

          1. handle

            Re: Solar monitor

            @YetAnotherLocksmith: The solar inverter will only produce an output if it is connected to the grid. It will not do anything if you connect it to an isolated load such as an immersion heater.

    2. TeeCee Gold badge

      Re: Solar moitor

      Re: Dishwasher.

      Sod the solenoids. Just get an old-skool dishwasher with proper pushbutton switches and an analogue programmer rather than one of the electronic ones. Then thump the "on" button after loading and you can just turn the mains supply on and off to play/pause it.

      Of course, if you already have an electronic one, it's almost certainly got a timer function built in if you RTFM......

      1. handle

        Re: Solar moitor

        @TeeCee: I agree sod the solenoids, but the trouble with an old-skool dishwasher (like I have) is that it has a ~3kW element, which is likely to exceed your panels' output most of the time. I gather the modern ones use much lower powered elements. I have a 900W "hotel kettle" which I use when I'm exporting power. Not only does it use a higher proportion of solar energy than a 2kW/3kW traditional kettle, but its smaller size means it is much more likely to be filled with the amount of water needed, rather than too much. It will probably never pay for itself, but it's satisfying to use!

        I don't understand your comment about timers - "play and pause" is to start and stop as the sunlight and house loads vary, not to delay starting and then running a normal program.

  16. Anonymous Coward
    Anonymous Coward

    Pi Scales

    I love the idea of the Pi Scales. I'd like it to store previous weigh ins and then say "You're doing well" if my weight is better lower than yesterday. It could also upload directly to my weightloss blog.

  17. James Boag
    Thumb Up

    RE Is this workable?

    Tell you next week, At present my "PiBell" project works as a doorbell, (Playing a couple of bars of AC/DC) your door bell has a sub woofer yeah !, Pushes a message to my android phone, Tweets, then post to facebook, Hoping to add more functionality to it soon, The same pi's also a cups server and contains a complete lamp stack (You do log your door bell activations don't you) Anyway follow the door bell at @raspberypibel on twitter

  18. SecretBatcave

    I made a project with the Pi

    Its measures how often the shard is in cloud. From that you can then work out how much cash the

    bourgeoisie* have lost through rubbish views.

    The comedy website is http://www.whatcaniseefromtheshard.com and the explanation is here: http://www.secretbatcave.co.uk/electronics/shard-rain-cam/

    and

    http://www.secretbatcave.co.uk/software/shard-rain-cam-quantifying-cloudy/

    *No Marxist leanings intended.

    1. Ian 55
      Thumb Up

      Re: I made a project with the Pi

      Fab.

    2. Lunatik
      Happy

      Re: I made a project with the Pi

      Genius.

      Nice website, Sir. You should gets some RSS on that.

    3. Anonymous Coward
      Anonymous Coward

      Re: I made a project with the Pi

      You typo'd: Even more if you subject is slightly reflective.

    4. trip0x

      Re: I made a project with the Pi

      This is quality.. great idea and made me laugh out loud :)

  19. GlenP Silver badge

    Automated Coffee Table Railway

    My current Pi project is to control a model railway built into a coffee table. The Pi (plus PiFace for simpler IO) will be located actually on the layout, inside a factory building. Train control is via a SPROG USB controller (located inside the pub probably) while the external connections for power, HDMI, USB and network will be brought out to sockets on the edge of the layout, although it will probably also run over wireless netowrkign with SmartPhone control.

    Software will be written in Python with fully automatic running or manual triggering via push buttons (I've got 6 spare input ports after using 2 for detecting when trains reach specific points on the layout).

    Glen

    1. Mister_C
      Pint

      Re: Automated Coffee Table Railway

      Excellent idea, but I'd be careful about controlling the train from the pub in case the fat controller decides on random alcohol testing

  20. Anonymous Coward
    Anonymous Coward

    Now these look like fun: http://www.piborg.com/home

  21. Benjol
    Boffin

    This is the kind of thing I need. I got the RPi, and it ended up sitting in a drawer for a few months while I tried to work out what to do with it. Recently I bought a PiFace, thinking that it would give me more ideas. Scratch has failed to inspire either of my kids unfortunately.

    And like lots of other commenters here, I don't have hod-loads of time to spare...

  22. Irongut
    Thumb Up

    Dropcox

    Best Freudian slip I've seen in a while. :)

  23. Steve 130
    Pirate

    I updated an old spectrum with mine.

    Number 9 on http://www.pcpro.co.uk/features/378817/ten-amazing-raspberry-pi-projects/3

    Video: http://www.youtube.com/watch?v=9R0jGUm8RpA

    1. pPPPP

      That gets an upvote from me. Do you have to tiptoe round it when it's booting?

      1. Crisp

        Do you get the freaky border around the edges when you load games?

  24. Nick Pettefar

    Xymon Server, etc.

    I use a battery-backed up RasPi for an Xymon server. It monitors all my routers, SANs, servers, cams, etc. I find it quite useful.

    Another RasPi is being used as an executive alarm clock. Another one is used as the heart of an old-time radio that plays random MP3 recordings of pre-war radio show recordings through a small valve amplifier.

    Another RasPi is a QRSS TX controller.

    Some Model A's work as environmental monitors around the house, sending back temperature, light, humidity and other values back to a master Pi server. These might be extended to control radiators/lights/curtains in a future project.

    I am thinking about replacing my Apple TV with a RasPi media centre.

    I am experimenting with FreeBSD on another Pi.

  25. Dana W
    Happy

    Ok, you got my attention at Mame emulator!

  26. Stevie

    Bah!

    Save yourself the cost of the kindle and buy a HDMI to VGA converter for about $20. Then, when you are in the server room you can dig out the Pi, connect it to any of the keyboards and one of the old (and therefore not-fit-for-server-use) CRT monitors lying in a pile in the corner and Bob is your mother's brother.

    Yes I know that's not the point.

    The laptop would be a great idea I'd be all over if the GUI was more responsive to the mouse. I'm seeing many issues that probably boil down to mouse-click duration set too narrowly and "pixel mat under the pointer" too small. Clicks often don't register, and the pointer must then be moved a little before another attempt is made. I'll figure it out if I ever care enough, but anyone wanting to use the Pi on the go is going to need better than this.

    The weather station and pub game ideas are fascinating though...

  27. Anonymous Coward
    Anonymous Coward

    Error in ratings

    "2 - easy as (sorry, statuary required cliché ahoy) pi"

    Your cliché meter is mis-calibrated. Surely "easy as pi" has to rate about 0.14 more than 3.

  28. Danny 14
    Go

    XBMC

    When the wife goes on a hen do in May I plan on cracking the back of the TV and installing the PI inside the TV and run XBMC from it. I plan to run a relay to power up/down the PI as necessary and judicious use of a dremmel to have some access ports/breakout cables (the TV has a HDMI on the side which I plan on using with a breakout HDMI socket from the PI)

    What can go wrong :)

  29. Christian Berger

    Possibly Infobeamer

    There's talk that Infobeamer, a minimalistic but powerful visualization package for Linux might run on the Pi.

    It makes it really easy to do things like this here:

    https://www.youtube.com/watch?v=LMHMV3hlTLk

  30. Neoc
    Coat

    "given a super-powerful computer, with infinite computing power shoe-horned into a coke can, what would you do with it"

    ...would anyone like any toast?

  31. Phil O'Sophical Silver badge
    Thumb Up

    VPN

    Two Pis, one at a UK-based friend with BT Infinity, the other at your non-UK home. OpenVPN, some configuring, and you get BBC iPlayer, Sky on-demand, etc...

  32. Chris_Maresca

    RFID/iButton Access Control system

    I'm building an RFID/iButton access control system for a warehouse where I have a workshop.

    Basically 3-4 readers, 2-3 doors, logging and a web interface (though not hooked up to the net). Also looking at bluetooth + phone app as another 'key'.

  33. Characias

    More fun with the Raspberry Pi

    I use mine to open the garage door.

    Full details: https://sites.google.com/site/opengaragedoor1/

    Video: http://youtu.be/xhilXRmknTg

  34. daveake
    Alert

    Thanks

    Thanks for including 2 of my photos.

    Thanks for not including my project that they came from.

    Strange combination that don't you think?

    Dave (Pi In The Sky bloke)

    1. dickiedyce
      Facepalm

      Re: Thanks

      Dave: Sorry! I'm not responsible for the photos, but if you post a link, I'll try and get it attached to the main article.

      1. daveake
        Happy

        Re: Thanks

        Cheers! http://www.daveakerman.com/?p=873 will do nicely :-)

  35. Clive Galway

    Signage system

    I just wrote a signage system for my company using RPis.

    It checks the timestamp of an openoffice presentation on a network share, and if it changes, reloads the presentation.

    Very simple, and a lot cheaper (In initial outlay and running costs) than using a dedicated PC, plus we can just zip tie the RPi to the back of the TV so it effectively takes up no space.

    All it took was a simple BASH script.

  36. sisk

    Security System

    Especially with the (relatively) new Raspi specific camera, the Raspi makes for a great security system. Get several of them, along with the above mentioned camera, and load them with software that either streams video out (if you have storage to burn) or clicks off a still whenever there's a certain threshold of change in the image. Pipe that to a server in your back room that saves the data. Extra cost: about $20 per Raspi for a cheap USB wireless card plus whatever the camera costs (I actually made plans for this before the Raspi cam was available). You'll need one more Raspi with a big external hard drive or an old PC to act as a storage node. The software is all in the Debian repository (though I don't have my list with me right at the moment to tell you exactly which packages you need).

    By my math when I first looked at doing this you end up with the functional equivalent of a $700 security camera system for about $250 total. Of course I haven't yet convinced the other half that we have any need for such a system and thus have not been granted the permission to spend the money.

    1. JetSetJim
      Thumb Up

      Re: Security System

      RasPi: £35.93

      Wifi dongle: £8.30

      RasPiCam: £25? Due for release in April

      Case: Optional, but might be nice - suspect a new case type will be needed to mount the cam on it (or drill a hole in a normal case and glue cam in place)

      PSU: I have a phone charger plug thingy with micro-usb, so assume that'll work

      Thankfully I have a NAS box so that's the total expense.

      Wouldn't mind a list of software, though :)

      1. sisk

        Re: Security System

        Actually using a NAS simplifies my software list. I was originally using HTTP to push the data around, but there'd be no need for that with a NAS, so all you'd need is the software to take pics whenever there's a significant change to be noted. You'd use motion, configured to save to your NAS with a filename that includes a reference to the camera and datetime stamp. You'd still want a control box with the ability to clean up old files probably, but with a good sized NAS it wouldn't be strictly necessary.

        The other option, video, would use streamer instead of motion, but the setup would be a little more work. I think it might also need a server to catch the stream. It's been a while since I put together the details.

        Or, if you want a REALLY nice setup, check out ZoneMinder. It's a bit overkill in my opinion, especially if you're only thinking of one camera, but it'd make things easy.

        1. JetSetJim

          Re: Security System

          ZoneMinder looks cool - lots of stuff to tinker with :)

          The only issue with the RasPi solution is possibly in making a waterproof housing for it if mounting it outside, plus making sure it doesn't take pics of stuff outside your property as that might get you in trouble.

  37. AlSmith

    Raspberry Pi Programming Competition

    We decided to build a GSM basestation with ours. The radio is quite expensive, and it took quite a lot of time, but it's great to see what a slice of humble pi can do... http://www.youtube.com/watch?v=GCcKgrzbix4

    We have also been running a competition with some cool entries from kids. Check out our website if you want to see some examples http://www.paconsulting.com/raspberry-pi-competition/

    If anyone is interested, next week we are running an awards reception at our tech centre for said competitionto showcase the next generation of geeks! You can register here: http://bitly.com/XGQz51

  38. OrsonX

    Yawn

    Yay, lets re-build yesterdays crap technology, I mean why?!

    1. Anonymous Coward
      Happy

      Re: Yawn

      C'mon now, are you a geek or an accountant who stumbled across The Register thinking it was a blog about double-entry bean counting?

      1. Because we want to build something, not merely consume other people's inventions.

      2. Because yesterday's technology to you is good enough for the rest of the world where people can't afford a quad-core whatever

      3. Because the opportunity cost and penalty for failure are tiny - I can stomach the loss of a pi more than I can my laptop

      4. Because geeks are some of the most innovative artisans on the planet, and this is our calling

      5. Because it's there.

      1. OrsonX

        I withdraw my yawn

        +1 to you Sir.

  39. plrndl
    Linux

    Great article. Wish I was 14 again.

  40. Crisp
    Go

    Geiger Counter, Green Screen, FM Radio

    Looks like I've got all the makings of a Pip-Boy here!

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