So here’s what the Second Doctor sonic screwdriver I built and carried around at Anglicon looks like on the inside. It took a few goes to come up with the best way to do things – or should I say, a functional way to do things – since everything had to fit in a 9mm diameter tube.

I took a few approaches, but eventually I went back to just using the original pen light’s switch – a spring which is compressed to close a very simple circuit, which used the metal housing itself as the return power conduit. So all the various elements ended up being shaped like short AA batteries, with power contacts at each end.

This involved occasionally making casts for new parts, to hold the active elements against each other. I made them out of epoxy glue, with forms made of various items, sometimes tape, but whatever was appropriate.

I ended up having to cut that form down a lot, after it was done, because it was too big. And I needed to keep some space from the other side of the speaker, so I built a spacer out of a wooden dowel, and glued it all together, then wrapped in heatshrink.

The rattle/buzzer is similar. Obviously it has to be longer, because the actual driver is an offset motor, the sort of thing used in phones. The big difficulty here was that there’s an actual physically-spinning offset piece, and I needed a way to allow that to be pushed down upon without jamming. The original piece was a bit of plastic on only one side of the spinning element, but that turned out to be inadequate, so I surrounded it with a wooden tube.

Plus of course in both cases the wiring had to be moved so there’d be positive on one end and negative on the other, so all these cast elements had wire grooves in them. Here’s one of those ends, nice and visible.

And so, I ended up with this totally modular thing which will let me swap out modules – even, say live – and have functionality change. I already know my next module, if I can make it work. It’ll be hard, given the tiny size, but it’ll be fun to try.

Here are two videos of the sonic in operation: Noises emphasised, Light effect emphasised. Even though it’s just an LED, I really like how the lighting works.

And stills:

Sonic, Idle

Sonic, Lit

Sonic, Light End

Screen Accurate

So, yeah! Second Doctor Sonic.