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My blogspot site is no longer updated. Most of the posts here are archived at www.srimech.com along with new content.

Wednesday, 30 May 2007

Theremin!


A few days ago at work we got some new computers in and decided to call one of them 'Theremin' since all the others were named after instruments and we were running out of ideas. A quick browse later and I found Art Harrison's web site on Theremins. This is built from his '2006 Minimum Theremin' instructions and I found it pretty easy to find all the components at Maplin. It's a simple design, meant more for demonstrations and science fairs than musical use - Art has designs for more sophisticated theremins on his site. I've no doubt reduced its musical quality by deviating from his design, but you can still get a tune out of it. I've left off the tone control - it's an preset on the board rather than a proper control - but you can alter the range quite adequately by adjusting the length of the telescopic antenna.

Sunday, 20 May 2007

Dan's from-scratch barbeque


Last weekend my friend Dan invited us all down for a barbeque. A generous offer anyway, but this had the added highlight that Dan had built the barbeque from scratch. It's a fine piece of engineering - perhaps not quite as stable as a brick barbeque but it served very well and cooked plenty of food for fifteen or so hungry guests over the weekend.

The construction materials are (so far as I remember) 1/2" steel bar and angle, some thin steel plate, steel mesh and those corner strips plasterers use - the closest thing most DIY stores will have to perforated angle. If anyone else has a go at this, my one piece of advice would be to avoid galvanised metal, as can give off some nasty fumes if heated. Compared to the quantities of ethanol usually drunk at barbeques though, it's probably a drop the ocean.

Dan also made a giant jenga set by cutting up some planed timber - a very quick and effective party piece. Pictures of that are in the gallery.

Friday, 11 May 2007

Sugar Fab

EvilMadScientist's sugar fabber promoted quite a lot of discussion in our office today. Using sugar as a fabrication medium is inspired, but we wondered whether we could use something more accurate than a hot air gun to fuse the sugar. Using a high-power laser would seem ideal, but I think there's a lot of milage in using a lamp (or lightbulb) and a moving lens or mirror to focus heat on a particular area.

Thursday, 10 May 2007

Ghetto 100Base-TX

Networking Today's top tip: Don't slam your network cable between a door and a door frame. You'll end up cutting out a section of damaged cable and assembling it as shown. Although, if I do say so myself, the slight over-exposure makes for quite a nice photo.

Top Of The World

attic Last weekend I went on a little exploration of my attic. There are two water tanks up there, quite a lot of wooden beams and lots of rockwool insulation. Not all of the rockwool is in the right place, so I've attempted to distribute it properly with a pair of sturdy gloves and a fancy dust mask.

Anthony Axford delivered a batch of quarter-boards of chipboard and some aluminium angle which I've used to board up some of my attic. Using the aluminium angle as guide rails I've been able to put down boards to create useful storage space while still allowing me to lift the boards up in case I need to do any electrical work in the future. The south side of the attic already contained quite a lot of wiring which I couldn't cover in case of overheating, but the north side was free of it so I've been able to create quite a lot of useful space there.

Happily, a quarter sheet of chipboard is exactly the width of the rafters in my attic. I didn't know that would be the case when I ordered them - it could be a coincidence but it's probably something deeply entrenched in ancient building codes that makes things a multiple of one foot sizes.

Wednesday, 2 May 2007

Tiny memory cards

microsd 2GB!! On that tiny thing? Crazy. In the gallery I've got pictures of that next to an 8MB Playstation memory cartridge, which is about 100 times the volume. If I could find it, I'd have a picture of my 8" floppy disc drive next to it. Kids these days. Honestly. Tsk.

I've bought this for my new M3 DS Simply cartridge, which promises to allow me to put some homebrew software onto my Nintendo DS. I was introducted to it by a friend at work who has ScummVM working on his DS using the same cartridge, but I'm mainly interested in writing my own software for it. At the moment though, I have no idea what that entails - I'm led to believe the thing has a couple of ARM processors but apart from that I know nothing.

Bed #2



A few weeks ago I thought it'd be a good idea to make myself a bed rather than buying one. After all, I'd get to make one to my exact specifications and it wouldn't look like anything you could buy from Ikea. In addition, I'd made a bed before and it had served me very well.

The thing is, when I say 'a few weeks ago' I actually mean 'over a year ago' and I've had the timber cluttering up my front room since then, and simultaneously been opposed to buying a proper bed because I'd already made that small initial investment. Since then other commitments kept appearing, such as fences blowing down and my employers who continually expect me to do the job for which I'm paid.

Last weekend I finally finished sawing, chiselling, filing and sanding the components and got the bed assembled, and to be honest it's not that great. My last bed - a bunk bed - creaked quite a bit but I was confident with it because I knew I had enough cross-bracing. The legs on this depend on the quality of the top joints and they're not that accurate, so in engineering terms it's a bit disappointing. Still, it is very solid. I'm mainly glad that all the timber is out of my living room.