affable-lurking

On on Dec. 16, 1947 - sixty years ago today - the world’s first transistor was constructed and tested at Bell Labs, New Jersey, USA. Those responsible for the device were William Shockley, the theorist and John Bardeen and Walter Brattain who actually constructed the first one.

What started life as a heap of precariously balanced parts…

…ended up kick-starting the microelectronics revolution.

Today’s equivalent to Bardeen and Brattain’s part is one of the myriad sub-millimeter sized black specks you’ll find on the PCB of just about any modern electronics. Yet even these dwarf their tiny sibblings on the silicon die of a CPU, where they are packed with more than 150 million to the square centimeter.

I’m in need of a high-voltage, low current DC power supply temporarily for an experiment in the lab, prices for these from the usual suppliers run into the hundreds of pounds. Given that all (all but the very best ones anyway) they consist of is a string of diodes and capacitors in a Cockcroft-Walton configuration, I decided to build one.

C-W generators are reasonably safe devices unlike their very similar cousins, the Marx generator. The voltage developed by the generator might be very high in both cases, but the C-W generator supplies very little current, whereas the Marx gen will deliver something more fatally akin to a lightning bolt. That’s not to say you can’t hurt or kill yourself with a C-W gen, just that you’ll have a bit of a harder time managing it. If you have an ioniser in your house, it will be very little more than a few stages of a CW gen and some resistors for further current limiting.

So, that’s the high-voltage, where does the coincidence come in? It happened that yesterday while flicking though my copy of the December CERN Courier, I spotted a feature on Cockcroft and Walton splitting the atom using equipment based around the generator bearing their name. I may going into the details of their achievement in another post, but for now a photo of them in their finery (and not just because I can then count this as an EDW post. Oh no…)

Ernest Walton, Ernest Rutherford and John Cockcroft.

I spent most of this afternoon attempting to attach two pieces of 0.25 micron Teflon tape to some larger Teflon blocks while wearing low-friction gloves.

It wasn’t easy.

Lately, I spend much of my working day the cleanroom, well , either of two cleanrooms.

Room-A is a pretty basic cap and gown type affair - the room isn’t really clean (class 100,000 to 10,000 depending on how often used; more usually high than low), the kit is really there to control access (limited kit = limited number of users) to the room and provide nominal clean standards. Room-B, on the other hand, is a bit more serious; usually class 1000, sometimes approaching class 100 after a few weeks of no use, you need to get properly kitted up to enter this room.

Yesterday I found myself in the changing room for room B with a camera, so here is a self portrait showing me about to start work.

Elegance this Wednesday is yards of blue nylon and nitrile. Or something.

I, on the other hand, managed to dissolve two of mine today.

Ok, they were both unknown quantities that had been rescued from a junk pile years ago and left to gather dust at home. Today I remembered them and took them to work to see if they’d be any use. A quick blast from the compressed air line removed much of the dust, so leaving them in their mounts for easy handling I gave them a rinse under the tap.

Only to see one lens start to dissolve and melt away - I’m now guessing it was actually a rather expensive salt plate. Bugger!
The other lens washed off fine, so still pissed-off about the first lens - and thus not really thinking - I gave the second lens a clean with tissue paper and acetone. It promptly frosted over and became tacky - a bloody plastic lens.

Two items that had sat on my shelf for near on ten years destroyed in a few minutes. The only saving grace was that both lenses were too scratched and damaged to have been much use anyway; the plastic one especially - it would strongly absorbs the light from my laser diode. The mounts are at least still useful.