Explaining the auto kitchen light plan

Since a few people seem interested/skeptical on Twitter, here’s a very quick explanation of a small update to the kitchen lights. Since getting a Current Cost meter it’s been obvious that the biggest waste of electricity are the halogen spotlights in the kitchen. (It amazes me that ordinary incandescent light bulbs are being phased out while at the same time many new houses are full of halogen bulbs, but that’s for a future post!)

Most of the time the two lights under the cupboards would be good enough, but the switch for those is a bit hidden away, so we usually use the five ceiling lights instead. The first part of the cunning kitchen light plan is to connect the two worktop lights to a Home Easy remote control ceiling switch. Now we could put an ordinary remote switch in easy reach next to the main light switch but where’s the fun in that? I got tentative spousal approval to use an indoor PIR remote control instead…

Results so far seem promising: the lights aren’t triggered walking past the kitchen because the sensor is looking inwards from above the existing light switch, and there’s often no need to resort to the manual switch to turn on the electricity burning main lights… which is actually quite lucky because they aren’t there at the moment!

Only temporarily removed due to some planned ceiling painting* but it was a good excuse to automate the backup lights.

* Well, it seemed pointless painting the tiny ceiling in the porch on it’s own, so the kitchen is getting a fresh coat as well.

My second CurrentCost development board circuit

My first attempt at monitoring gas use with a CurrentCost development board was partially successful. I could get a reasonable idea of when the boiler was firing but I didn’t really find that information particularly useful. So, plan B was to actually count the pulses from the gas meter. The second circuit, which is described in the 8. More about triggering section of this 555 timer page, has been running ok for a few weeks now, so I’m thinking about actually soldering it together. Thanks to Richard for suggesting VeeCAD, which led me to TinyCad, this is circuit number two (much easier than using MS Paint!).

I’ve been using R1 and C1 values of 122k Ohms and 47u F for the 555 timer, to trigger an output pulse that’s just long enough to get transmitted by the CurrentCost development board (~6 seconds). I may yet tinker with the timing to make it long enough for three transmissions; the time between pulses on the gas meter is long enough and it might make receiving pulses more reliably.

Thanks to Mark and Andrew for some ideas for laying out a circuit on strip board, here’s what I hope is the same circuit using VeeCAD:

Might get the soldering iron out next time Jo’s away!

Update: For plenty more advice on moving from breadboard to a more permanent prototype, have a look on the Evil Mad Scientist Laboratories blog. (11 March 2010)

Update: Finally got round to pulling everything off the breadboard and soldering it together…

…and it actually still works! (14 March 2010)

Do you have a low power home server?

I’ve been meaning to post a follow-up to ‘Cheap low power home server options‘ for a while; partly for my own curiosity (I wonder what server I’d choose if I was looking now), and partly because more and more people seem to be looking for one (based on the highly scientific hit count for the original post, which is almost twice as popular as the second place post).

Rich is considering a SheevaPlug for example, some neat looking machines crop up on the Smart Home Blog now and then, and of course there’s the hugely popular (in Hursley at least!) Viglen MPC-L, which appeared just after I got my Netvoyager (still very pleased with my choice- up for 425 days and counting!)

The question is, what server are you using? And would you recommend it?! It’d be great to hear some experiences, whether you’re happy fighting something as small as a NSLU2, decided on a server anyone could use, counted the pennies, or splashed out on something more expensive.

Update: sadly Chris has discovered that the MPC-L and LX-1000 have been discontinued. (17 February 2010)

“so it looks like Viglen dont sell the MPC-L anymore and Netvoyager don’t sell the lx1000 anymore. What’s a low power geek to do?” @yellowpark

A few alternatives suggested by @rikp, @dllmr, @ScaredyCat, and @netcompsys:

Update: A couple more options which look quite tempting. (4 May 2010)

  • GuruPlug (the SheevaPlug2.)
  • O2 Joggler (very nearly got one of these when they were on special offer! Looks like a very useful device with the bonus of a responsive touch screen.)

Update: I gave in and bought a Joggler while they were briefly back on special offer, although I haven’t (yet) moved anything off my old Netvoyager. If you missed out on the Jogglers, the Aleutia T1 Fanless PC looks like another possible contender for home server duties. (6 July 2010)

Windy Miller

A while ago I was reading about compressed air energy storage in natural underground caverns (probably in something from the IET) and I was surprised that something similar doesn’t get mentioned more along with renewable generation like wind power. On the other hand, the unpredictability of wind does seem to get mentioned as a limiting factor much more; understandably it’s a little hard to react to peaks in demand and energy price if you have no control over when the wind blows.

Given the growing number of off shore wind farms, I wondered if wind energy could be stored by pumping sea water out of something like a large diving bell, allowing the water back in to generate electricity on demand. Turns out that ‘something like a large diving bell’ is a submerged, open bottomed, anchored caisson.


(cc) some rights reserved. Thanks to phault and Zach Putnam for their photos.

The idea might not get a lot of air time but parliament seem interested in storage techniques in general, and there are examples of the possibility being researched and developed, so there may be a future for renewables without as much baseline capacity required from non-renewables. What do you think?

Update: not for offshore wind farms, but @USR_VRB pointed out a very interesting post about a compressed air project, where the air is used to improve the efficiency of gas powered generation. Some good discussion and links in the comments as well. (4 Sept 2009)

Update: there’s a much more in depth discussion of this idea on Salient White Elephant, and it doesn’t look promising unfortunately. (10 Sept 2012)

My first CurrentCost development board circuit

The result of a fair bit of googling and a weekend of hacking is… [drum roll]… a circuit to connect my gas meter to a CurrentCost Envi using a nice little dev board from CurrentCost


Now I’m much more familiar with messing about with software, not all this messy hardware stuff, so I’m really hoping to get some feedback to improve this early prototype!

So, my theory is that the stuff on the left will trigger the timer on the positive edge of the pulse from the gas meter. R1 and C1 control the 555 timing; more on that in a second. And the stuff on the right (LED and the CurrentCost dev board) should be triggered whenever the gas meter is running and emitting pulses. It all seems to work, except that I can’t seem to get the timing quite right. The gas meter takes about 1m40s between pulses, and I can choose values for R1 and C1 that trigger the output for the right length of time when a single pulse is detected, unfortunately subsequent pulses don’t keep the output on as I was hoping. The best I’ve managed is with R1 = 3M ohms and C1 = 100uF, which does stay on as long as there are pulses from the meter… unfortunately just for a little too long at 5 minutes. Still, at least the CurrentCost Envi will get a reading all the time the boiler is running, and it won’t get stuck on if the meter stops on the portion of the dial where the reed switch is closed.

Any comments with glaring errors, small problems, improvements, or a completely different way to do it?!

Updated: looks like I was having problems with left and right in my first description! Hopefully I’ve got them the right way round now! (2 July 2009)

Update: for an alternative approach (latching a pulse and clearing it when the cc board transmits) take a look at the circuit and photos on John’s blog. (9 July 2009)

Update: an on/off indicator for the boiler hasn’t been all that useful. Instead, to count pulses, I’ve now modified the circuit to simply trigger an output pulse that’s long enough to get transmitted by the CurrentCost development board (~6 seconds). The circuit is described in the 8. More about triggering section of this 555 timer page, with R1 and C values of 122k Ohms and 47u F. (25 January 2010)

Update: posted some more info. on my second CurrentCost development board circuit. (23 February 2010)


I’m getting pretty close to getting the gas meter hoked up to CurrentCost. Not quite the finished thing, but was pretty excited when I got this working…


It’s a 555 timer circuit (using a low power 555 chip) which I’m hoping will keep the CurrentCost dev board transmitting a value as long as the gas meter is running. I’ve since added a capacitor to trigger on an edge so it shouldn’t keep transmitting if the meter stops on the ‘pulse’ position, which is probably around 1/8th of the time on my meter.

I wasn’t quite sure everything was working when I finished last night, but it does seem to do what I want when I was showing Jo this morning, so hopefully all I need to do is get the timing right for the gas meter, rather than me hitting a button every few seconds. More details to follow if it does work.

Recipe for a Virtual World 6: User generated content

If you even remember the previous posts, you may wonder what happened to 4 and 5. Unfortunately I got bit stuck on money (which was going to be the forth, but I never quite decided whether an economy is directly relevant to virtual worlds- my current suspicion is not) and physics (which was going to be the fifth, about the different approaches used to construct virtual worlds, rather than physics simulations), but I kept getting distracted! If it wasn’t for user generated content, I doubt I’d be the least bit interested in virtual worlds; I get bored being a spectator in computer games very quickly.

Luckily I don’t have to write a whole post about what’s so important about user generated content, because Dale’s done that already! Jonas’ “Dead Gnomes as Enterprise Collaboration Tools” post is also worth a read as it shows that the goal of content creation can often be something other than content which is produced. The content is just a means to an end, and user generated content can take care of the long tail requirements that virtual world developers would never otherwise get to. How far up the list of priorities would dead gnomes be?! And how long would you have to wait for the opinionator?! (My current all time favourite gadget in second life.) Even the opinionator is a luxury when you can just stack up cubes, but one that makes for richer interactions- you can’t have too many ideas like that to make up for the loss of real world interactions if virtual worlds are to be the next best thing.

News that professional design teams are getting tools to collaborate on content creation inside the world they are building makes things even more interesting, further blurring the lines between designers and users/producers and consumers.


(And I almost forgot to mention MQTT enabled ducks and UK energy price turbines on ReactionGrid!)