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Anyone who has watched Torchwood will recognise this image.

wriststrap

That’s Captain Jack’s Vortex Manipulator. It’s a multi-purpose tool, I guess that means the writers can make it up as they go along. One of the things it can do is time travel with some unspecified limitations. During crossovers with Dr Who the Doctor makes disparaging remarks about it. Also there are a couple of times in Torchwood episodes when time travel would have given Jack an easy solution to the current problem but he doesn’t use it.

For me the coolness overwhelms the (inappropriate in my case) gayness so I decided to make one. Not exactly the same, though. I wanted some differences. I wanted to get rid of the aluminium look for a start because to me it clashes. Something more steam punk like copper would be better. And I wanted it to actually do something. Not necessarily something useful but something.
So here is mine.
mywriststrap1

Yes, it is a bit bigger, but it actually does something. It detects Daleks. Actually it does some other stuff as well. The black square is actually a Microtouch which has a bunch of stuff wired into the smallest touch screen I could find. If you go to the link you’ll see that I didn’t have to build the electronics myself, except that I did have to get the ON button exposed using some simple soldering. You can just see the button above the top of the screen. The Microtouch’s button is actually on the underside which is too hard to reach.

Assembling it was quite tricky. The Microtouch is embedded in a carefully shaped block of an expoxy mixture embedded with ceramic particles. This makes it feel like stone. Then I sprayed the top with copper paint (nicer than aluminium). There are no attachment lugs on the Microtouch and it seems kind of fragile. So it slots into the space in the epoxy snugly enough to hold tight with no screws. The leather on the bottom holds that end down. If I had to I could lever it out again.

After that it was a lot of messing about with leather, something I had not tried before and Mrs had to pitch in with the sewing after I did the cutting out and gluing everything in place. The domes and stuff were hardest to get right because they don’t handle lots of layers of leather. It is bleached sheep skin dyed to get this colour (had to figure that out too).

This shows it closed up. The battery (a 1000mAh lipo which is very flat) is tucked into the underside of my wrist.

mywriststrap2

There’s a trick here. If I open the near side it opens up as shown in the first image. But if I open the back domes I can get at the underside of the electronics, enough of them anyway. I’ve made various incisions into the oval block of epoxy to get at (clockwise from the left) the reset button, the ON button (the wires lead from the PCB to the button embedded in the top), the USB port, the Micro SD card slot, and the power supply.

mywriststrap3

Remember I said it should do something useful? I can program this thing in C and load the code down through the USB port. Actually I had to trim a lot of the plastic off my Micro USB cable to allow this. It was either that or make the gap bigger in the epoxy which would have weakened the structure. But back to programming it. The Microtouch has an accelerometer on board so I built a Dalek detector based on that. It does not detect real Daleks (did I need to say that?).
It looks a bit like a radar screen and it goes red with a tiny image of a Dalek when it gets some movement on the x-axis. After a while it goes away again. The positioning of the Dalek and the time it appears is randomised. This stretched some very old muscles for me because back in the ’70s I did some assembler programming on micros (they were a lot dumber back then). But since then I have got used to more-or-less infinite amounts of memory and vast off-the-shelf libraries of stuff to do simple things like generate random values. The Microtouch does have a nice library for generating shapes like circles etc which helped with the geometry, but randomising I had to figure out for myself.

So, target achieved. It looks cool and it does something kind of useful. I may yet think of something actually useful yet but this does it for now.

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