Tuesday, 28 April 2015

Soldering: not so scary afterall

I'm planning to present a demo of Core Rope Memory at this year's Dublin Maker but there are some skills I need to develop before I can start working directly on that demo. Number 1 on that list is soldering.

I've always found soldering pretty intimidating, which is why I've never tried it before. Turns out it's not that hard! Just over a week ago I put together a silly flashing heart on my first try:



And then the eldest decided she wanted in on the action:


We twisted some copper wires together to give her an easier target than a tiny component, but I think she'll be ready for something more difficult very soon.

There will be two of these in the post as soon as they're back in stock :)

The main reason I wanted to learn to solder, was to put together this puppy:
https://learn.adafruit.com/adafruit-led-backpack/0-54-alphanumeric

Which I have now done!


Monday, 27 April 2015

Pretty Bits

As part of my Core Rope Memory project I've devised a binary encoding I call PrettyBits.

Why a new encoding, you ask? Well it turns out that ASCII has certain features that make it a bit ugly when used in my jewellery. Even if I just use 7 beads, (ignoring the leading bit that doesn't get used in basic ASCII), the two leading bits are always one for lower case letters, and there's a bias toward 0 on the lower order bits. I think this leaves the piece messy and unbalanced.


The effect is exaggerated here by the nylon beading string (a failed experiment), but it's also evident in the photo from my previous post:


(Both pieces have most-significant bit on the right in these photos).

Since ASCII was an arbitrary choice of encoding anyway, I started thinking about what I would like in an encoding for this jewellery, and I came up with three things:
1) Minimize zeros - the more threads through beads the neater it will look
2) Minimize strings of zeros - a thread weaving in and out of beads will look better than one going around three bead in a row
3) Balance the zeros between the left half and right half of the piece

I decided to use 7 bits, because having a central bit is nice, and because that gave me room to include lots of punctuation and the Irish accented vowels.

The first thing I did was generate a list of all the bit strings from 0000000 to 1111111. Which I ordered according to the rules above. Then I used the data in
http://www.queensu.ca/psychology/hiplab/Publications/Recentpublications/Mewhort_RP_15.pdf 
to produce an approximate frequency ordering including punctuation and capitalisation. The two lists were zipped together, so that the most frequently used characters got the prettiest bit-strings. I used that list to make this webpage work:

http://coreropememory.timui.org/
(edited to update link)



Here's the first piece made with the new encoding! I'm not very happy with the photo, but I think it just about shows that the new encoding is much more balanced. (I think it's very evident in-person).

This bracelet (no clasp yet) was made with found copper wire, so it's not hypoallergenic. The previous design is the best hypoallergenic solution I've come up with so far, though there are some high-end materials I can try if someone wants to order the wire-style above for sensitive skin.

I'll post soon about the more electronics-y side of this project, including my adventures with soldering and my new Arduino!

Tuesday, 14 April 2015

Homemade Othello board

I'm sort-of amazed that I never posted about this before. We made it almost a year ago:


We couldn't find an Othello set anywhere in Cork, so we decided to make one.

I'm sure I had planned an elaborate post giving all the details, but you'll have to make do with what I can remember :) The 'case' is just a cheap cardboard file which opens up to reveal:


The grid is cotton string glued down with Bostik. We wanted something textured to hold the pieces in place, and this works very well. (The sides need to be weighed down to stay flat, hence the cup).


The boxes for the playing pieces are made from thin card, and they fold up with the pieces inside when the set is being put away.


The pieces are made of circular stickers, stuck to the black card, and then cut out.

Et voila!

Sunday, 5 April 2015

Core Rope Memory

This is a project that's been brewing for a while. I'm not even sure where I first heard of Core Rope Memory, but it didn't take me long to think "that would make amazing jewellry".


Core Rope Memory is a type of read-only memory that was used in the Apollo Space Program. Each bead in the picture above is a ferrite core which interprets a bit on each of the the word line wires (green) that either pass through it (1) or go around it (0).

I'm using the same principle to encode text using embroidery thread and glass beads. It can't be read unless you're willing to painstakingly follow the embroidery threads, but I hope to eventually be able to make wearable jewellry that can be read to a screen.

The first prototypes are finally ready, and I'm super excited.




The bracelet I'm wearing encodes the phrase "for the benefit of all" -- the motto of NASA.

I have plans for improving the design, including hiding the back of the stitching with another ribbon on which I'll write the encoded phrase. I'll also be developing a necklace.

I hope to sell these as custom orders at Octocon this year, and they should be up on my Etsy shop as soon as I get that sorted out, but you could leave a comment if you're desperate to order one now :).