Weather Balloons and New Arduino Shields Have Arrived

Weather BalloonThis week I received several very exciting parcels of stuff, for my near-space photography project.

First was my weather balloons and parachutes, which came from Flow-Tronic, a company in Belgium. What a weird package, two bright orange plastic parachutes and two clear plastic bags with what are essentially giant 1.5m long condoms in them! The really extraordinary things is that although the balloons will start out at about 1.5m across when inflated, they will expand as they rise (due to the drop in atmospheric pressure) and will end up about 7m across before they burst. That is frickin’ huge!

The next packages to arrive were some new electronic gadgets for the tracking and communication part of the project. After not having much luck with my Navman Jupiter GPS modules (struggled to get a fix), I decided to bite the bullet and get a decent one, as well as the brilliant GPS and SD Card Logger Shield from Adafruit, built specifically for the Arduino. This comes in kit form, so will require me to get my soldering skills back up to scratch.

GPS and SD Card Logger KitI also bought a Cellular Shield from Cool Components which gives you SMS, GSM/GPRS, and TCP/IP capabilities to your Arduino project. I’ll be using it to send SMS messages of the units current location from the above mentioned GPS receiver. This should allow tracking of the weather balloon when at low altitudes, and hopefully aid in recovery when it comes crashing back to earth! This means I will have two stacked shields on my Arduino, so this will require some careful planning to make sure they won’t interfere with each other.

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Projects for the year

I’m constantly thinking up ideas for projects I’d like to do but never seem to find any time for them. Or when I do I can’t decide which of them to tinker with so I end up spending flitting between them and achieving nothing. I’m determined to tackle some of the bigger ones this year, as this is the stuff that I truly enjoy. So I thought I’d write a list of them here, so I at least have a sort of To Do list of projects that might help me focus on them a bit more.

Pyro Fountain Tools

DONE. Ok, this one is here just so I know I’ve crossed off at least one! You can find out about these in previous posts on this blog.

26 Degrees of Separation

A photogrpahy experiment that I’ve been meaning to do for a very long time now. It involves taking a picture with a disposable camera then giving it to a friend to do the same, and then they pass it on to someone else and so on. The idea is that hopefully if one of the cameras ever manages to reach person 27 in the chain they will send it back to me. Once developed I should then have a set of 27 photos, starting with me and ending with someone 26 inter-personal connections away from me. These will all be published on the website 26degrees.org

This one has been on my list so long that I think  the cameras I bought for it are probably out of date by now and I’ll have to get some more! I really want to do this soon as it could take a long time for any of the cameras to make it back to me, if they ever do that is.

Near-Space Photography

Arduino GPS Tracker

Arduino GPS Tracker

This is something I’ve been thinking about for a couple of years now after reading about it in the fantastically inspirational, and snappily titled, book “Makers: All Kinds of People Making Amazing Things In Their Backyard, Basement or Garage“. It featured details of two amateur aerospace fans who launched a weather balloon into near-space with a digital camera on board that captured some beautiful images showing the curvature of the earth. What was more impressive was the low budget they had managed to do it on (~$500).

This really captured my imagination and I’m now on a mission to launch my own in a similar style. The real bonus here is that it covers so many of my interests as it involves science, electronics, photography, tracking and programming. I’m making some progress on this already; I’ve been busy playing with a GPS tracking using my Arduino microcontroller and a separate GPS unit, and I’ve just ordered two suitable weather balloons from a company in Belgium. There will be a LOT of work to do for this if it has any chance of success, but the aim is to launch in late summer/autumn of this year.

I’ll write more detail on this one soon.

Social Media iPhone App

Like all good ideas this one came from a lunch time chat down the pub! Me and my mate Jay came up with an idea for a social media name checking service, and decided to build it into an iPhone app, seeing as that is the latest craze!  I will be building the API and other server-side code while Jay builds the iPhone app interface. Still in early stages, but keep an eye out for the launch of uniqapp.com.

Ball Mill

Yes this is still on my list. I made a good start on this last year with building a 12v power supply, but I then made a prototype ball mill which was far from functional! I didn’t even get round to putting any details on here, although I might do later. I need to rethink my design and make it much simpler. I’ve been looking around on the UKPS forums at other users’ home-made mills and will be taking some inspiration from them. I’m keen to get this one done as it’ll mean I can start some proper experimentation with my own black powder for simple fireworks.

Testing My Fountain Tools

After completing my first set of fountain tools, I made a few test fountains to see if they were any good. Here is a video of two of them.

The first is a simple 12g portfire mix with 2g ofadded airfloatcharcoal to give the normal orange sparks you would expect from what is essentially just a black powder mix. The second is another 12g portfire mix with 2g of added aluminium powder (size #40-100), which gives a proper fountain effect of silver and gold sparks.

When I say portfire mix I literally mean the contents of a portfire! I still haven’t finished my ball mill for making black powder so this is a reliable substitute for now.

I was quite surprised that the aluminium produced both silver and gold sparks (or at least that’s what it looked like). Hopefully someone will explain this to me at some point!

The tools worked ok, but there were a couple of small issues I will need to correct when I make my next choke former.

Firstly this one had a tiny lip on the top end of the spindle, caused by an inaccurate bit of turning on the lathe. It was tiny, but unfortunately on each fountain I made it snagged on the way out and pulled off a bit of the clay choke. Not a big problem as the choke was deep enough for it not to matter, but just frustrating that the finished product was neat.

Secondly I think I need to try and taper the spindle a bit to make removal easier. i know other tools you can buy are very fractionally tapered tward the end, but as yet I don’t know how to achieve this. I’m not sure the lathe I use at college can do this and trying to do it by hand would probably look awful.

I’ll investigate and see what options I have, otherwise I’ll have to stick with it for now.

Overall I was very pleased with my tools though, they did the job and the basic fountains looked great, very satisfying!

Making Pyro Fountain Tools

Fountain Tooling SetOver the last 6 months I’ve been taking a metalwork evening course at a local college. I wanted to make something I might actually be able to use so decided on a set of fountain making tools, to replace the ones I bought on eBay a while back.

The fountain tool set I already had was ok, but nothing special. The base is wooden and the rammers were really crappy wooden ones that weren’t very well made. The only really quality part was the spindle choke former. I also thought that it’d be good to only need one base unit, and have detachable spindles of differing sizes, rather than having to have a full set for every size of tube and choke diameter I might want.

So I decided to make a single aluminium base plate (should last a bit longer than wood too) with a screw thread in the centre, where different spindles can be screwed in. Each spindle would need a rammer to go with it that had a matched size hole down it’s centre. As I currently only have 3/4″ internal diamtere tubes I though I’d start by making a couple of spindles of that size, but with different choke sizes so that I could experiment with them later.

Fountain Tooling DiagramI spent a few weeks learning how to use a metal lathe and milling machine, which was really enjoyable, before risking making anything for real (as I had to buy the decent materials). I also drew up diagrams of what I wanted to make to try and explain it to my instructor (who preferred not to know once the word ‘fireworks’ was mentioned!). I tried doing my diagrams by hand but after so many alterations and rubbing out I reverted to doing them on the computer (using illustrator) which is much easier for me.

I decided to use aluminium for the base plate and rammers as it is ‘non-sparking’ (as far as metals can be), comparatively cheap and also easy to mill and turn on a lathe. However I chose brass for the spindles which is a little harder and I want them to retain their shape nicely under all the bashing they will receive.

So over the last few months I’ve made the tools you can see here, so far a set of three rammers, one base and one spindle. The spindle is 3/4″ diameter at the base and has a 6mm diameter choke former on one end and an M6 size thread on the other. I decided to start with two choke formers, with 6 and 8mm spindles, although I can make a bigger range later. Currently I only have the 6mm one (which is actually ~5.5mm so it can fit comfortably into the rammer with the 6mm centre hole). I have the 6mm hole rammer, and also the 8mm one ready for when I make the next spindle.

I’m also considering making a 7mm one too, so I have a set of three different 3/4″ foutnain tolls, with ~6, 7 and 8mm chokes. Apparently a choke size of 1/3 the internal diameter of the tube is ideal, so for a 3/4″ tube this would be roughly 6.35mm. At the moment the 6mm and 8mm ones I’m making are a little either side of that when you take into account the slightly smaller size used for the spindle (~5.5mm and ~7.5mm respectively), so a 7mm one will nicely meet this requirement as it’ll actually end up about 6.5mm. By the way I’m working in mm for the choke sizes purely out of preference as I find it easier than working in fractions of inches, and I think that 1mm increments in size are ideal for getting a good range of sizes.

I’ll post more photos when I have a the full set, and also when I test these for the first time.

View full photo set on Flickr

Fountain RammersFountain Choke Spindle

PHP Quine

I was reading the Wikipedia page on Quine programs, which are computer programs whose only output is their own source code. At first glance this sounds simple until you think it through, your mind ends up recursively parsing pseudo code! It took a while to get my head round how they work, but in the end it kinda made sense.

I decided to port one of the given C examples into PHP as an experiment, and here is what I came up with (I think it’s correct at least!).

<?$a='<?$a=%c%s%c;printf($a,39,$a,39)?>';printf($a,39,$a,39)?>

If you run this in PHP it should, well, output the above! Try it and then diff the output to the original source. Fingers crossed it should be the same.

It seems that the ‘challenge’ is to find the shortest possible quine in any given language. Since making the above I have found other PHP examples that use a very similar approach but cut down the code even further, such as this nice example from Komea Pimeässä:

<?printf($q='<?printf($q=%c%s%1$c,39,$q);',39,$q);

It uses some nice PHP shortcuts to remove unnecessary characters, like dropping the trailing ?> and putting the string assignment ($q=’…) as the first parameter of the printf call, instead of declaring it outside the function call and then referencing it again which wastes characters. It also uses one final difference from mine, and one which I wasn’t aware of, and that is using numbered specifiers in the printf function (%1$c in this case), so he can reuse the first specifier (%c) twice in his string without needing to declare it twice in the function call. Nice.

I don’t think I’m likely to find any way of shortening that further, but I’ll keep thinking it over.

UPDATE (15 minutes later):

I just had a thought on this, It may be considered cheating but surely this is a tiny valid PHP quine:

Q

Or, in fact, and text. Why do we need to actually break into PHP mode? It’s still a valid PHP file, and it will indeed output only it’s own contents, but it does just seems like a dirty trick. It doesn’t seem right that it doesn’t actually include any PHP statements.

After thinking of this, I had a more detailed read of the Wikipedia article for any rules. In fact it mentions that someone once submitted an empty file as the shortest possible quine in a C programming competition. They did however win the “worst abuse of the rules” prize. So maybe this single caracter PHP example just another, albeit not quite so short, example of the same abuse of rules? I’ll let someone else argue over that!

Arduino has arrived!

ArduinoMy Arduino has arrived, feeling very geeky now. I haven’t done any electronics in quite a while, so looking forward to finding something to do with it now!

First quick script fades three LEDs (Red, Green and Blue) through the colour spectrum. Unfortunately I don’t have a blue LED to hand so the effect is a little lost, but the principle is there at least!

Making a Ball Mill – Part 1

Now that I’ve got all the ingredients and bits together to start making some black powder samples, I’ll need a ball mill if I want to make decent BP. The idea of the ball mill is that it grinds the chemical powders down until they are incredibly fine which allows them to mix together much better giving a much faster burn rate than in their raw state.

The principle is simple, you have a cylindrical container which is part filled with heavy lead balls (other balls could be used as long as they are also a non-sparking material). You put your powdered chemicals into the container along with the balls, and the while on its side the container is rotated, usually by the container resting between two rollers one of which is powered by a motor. This keeps the balls moving and colliding with each other, which pulverises the chemicals.

Now, I’ve not used one of these before so I will be experimenting to find the best speed of rotation, and also how long you need to mill for to get the best results. From all the reading I’ve done you are looking at a few hours milling time to get the best results.

I purchased a geared 180rpm 12v motor from eBay, which should give high torque and have no problem rotating the container (which will be quite heavy). I will probably use a belt drive from the motor to a pulley on the end of one of the rollers. This will allow me to reduce the speed further by adjusting the pulley size, to find the optimal speed.

I also purchased s heavy duty plastic container and some lead balls. My container is relatively small (about 17cm tall by 9cm diameter), but should do the job for small quantities. My lead balls are 17mm diameter and I have 50, which takes up about a third of the container. Ideally i think I should have more than this to fill it about half way, but we’ll see how I get on.

First job now was to find a way of providing a consistent 12v DC supply to the motor. It just so happens that this same week Matt, a guy I work with, had converted an old PC power supply to a lab power supply unit, which takes advantage of the existing 3.3, 5 and 12v supplies generated. Inspired by this, I decided to harness the 12v supply from a PC PSU as my power supply, which would not only be reliable but also came in a handy enclosure. Unfortunately I didn’t see Matt’s article about it until afterwards, but I had found this useful website article which detailed the PSU circuit basics.

After ripping the PSU from an old PC in my loft, I realised it didn’t have a power switch, which would be required to easily start and stop the ball mill. So I set about adding one that I had lying around. It fitted perfectly in the hole where all the old power cables came out of, and as I would only now need a single pair of cables coming out, I mounted in there with an improvised plastic plate and some screws. Following the wiring details from the article mentioned, I removed all but the cables I would need, soldered in a link on the circuit board that ensured the power remained on after pressing the power button, and generally cannibalised the innards.

I took an old cable exit grommet/sleeve from a pair of defunct hair clippers and attached this to the PSU, so that the 12v power cables could exit the unit through one of the air grilles without chaffing of damaging them. Then I rewired one of the male and female power supply connectors from inside the PC, so that the motor could be attached and detached from the PSU at will. This means I may be able to use the same PSU in fitire for other projects that require a similar supply (maybe a star roller next!).

After putting it all back together it looks not too shabby and works like a dream, plus the new power switch has a built in LED which adds a nice little touch!

The next step will be to build the rollers and pulley system to actually do the work, so I’m just trying to get my hands on some roller bearings and suitable materials.

View full photo set on Flickr

Testing my new 3/4inch pyro fountain tooling

I purchased a couple of fountain tooling sets from eBay, to start experimenting with simple fountains and to test my BP when I get round to making some. I got 3/4in and 1in sets, which comprise a base unit with an aluminium disc which fits the internal diameter of the tube, and an upright spindle to form the choke.

The paper tube (I was making a 3/4in one) is placed over the disc so its sits firmly on the base, and then a small amount of bentonite clay powder is poured down into it. Using the hollow wooden dowel it is compressed with a few blows from a mallet which makes the clay powder go rigid. This creates the top choke of the fountain and saves having to drill one out later.

The composition is the poured in a bit at a time and rammed to compact it as necessary until you have the amount required. Then another layer of clay is added and rammed to give your bottom bung. When removed from the spindle you have a nice neat fountain with a choke hole about 1/3 the diameter of the tube inner. A short length of Viso fuse is then inserted in there and voila!

As I’m still very new to this and just itching to test the new tools I didn’t have any home made composition to use, so instead I used the contents of a port fire as my fountain comp. Obviously the effect wasn’t going to be anything special but it would do the job. I’m not sure of the exact composition of my portfires but they burn with a slightly green flame.

Obviously when put into this fountain you’re increasing the burning area, but the choke meant the exhaust was actually slightly smaller than the original portfire diameter. So what I got was a much more intense faster burning version of the portfire, with a much more noticeable green and some very faint drossy sparks coming out. Nothing too exciting but still quite satisfying as this was my first fountain of any sort!

The burn left a build up of dross deposits on the choke which you can see in one of the photos. I guess this would become an issue for longer burns, but in this case the composition didn’t quite fill even half the full length of the tube so it didn’t have a chance to cause too much blockage.

Here is a video of the fountain in action…

Making a small sieve set for pyro chemicals

As I’m just starting out into making some basic pyro (rather than just firing it) I decided I’d need a mesh sieve set for sorting and checking the granular size of chemical powders. With some inspiration from Cooperman435’s home-made set I saw some time back I decided to make a small stacking set.

I purchased a selection of 9 small mesh squares (10x10cm each) in grades from #10 to #300 (holes per inch) from eBay (£8+pp). Now obviously this won’t meet all my needs as I progress, but it’s a good start I think. I bought 10 really cheap plastic food tubs from Sainsbury’s (350ml, 34p each), and using a junior hacksaw cut the bottoms off of 9 of them, keeping one as a bowl to sieve the chemicals into.

I placed a non-stick baking sheet (baking tray with no lip) onto my hob to heat it up and then placed one of the mesh squares onto it. With the lid still on one of the tubs I pressed the cut edge down onto the mesh with some light pressure applied as evenly as possible. After a second or two you can see and feel the plastic edge start to melt into the mesh. I checked all round to make sure it had melted right around the tub’s edge and then moved it and the tray off of the heat. After a few seconds cooling down the plastic sets and you can pull it away from the baking sheet.

My first attempt didn’t melt all the way round the edge so I had to redo it but after that it was really simple to do the rest. I also found that you have to keep the pressure quite light but as even as possible other wise once the plastic starts to melt the edges of the tub would slide and deform out of their circle shape.

I wrote the mesh size on the side of the tubs in permanent marker. When I’d finished them all I carefully trimmed round the bottom edge of each tub with wire cutters, removing the overhanging mesh. In order for the tubs to still stack I needed to trim right up to the very edge of the tub, also removing the outer lip of melted plastic that had formed as it squeezed out. If you’re doing this be careful as the ends of the cut mesh wires can be sharp around the bottom outer edge of each sieve so watch out for scratches!

That’s it, they all stack nicely now and make a very compact set, suitable for grading small amounts of chemicals and compositions. About 2.5 hours total time to make this set.

View full photo set on Flickr

Video

See me melting one of the tubs onto the mesh square, exciting times!