Progress (lack of). Excuses etc.

A project log for Chymes

Cheap, nondestructive atomic analysis in real time.

A. M. AitkenA. M. Aitken 07/09/2016 at 22:200 Comments

It's to my shame that at a time when I want to devote my full attention to a project that 3 more important things come along. The car at the top of the road that rolled down and largely destroyed the front wall of the garden about three weeks ago and the small tree falling over onto next doors fence and ripping the wires out of my satellite dish which happened yesterday don't even figure in the 3. Only the British sense of irony is audacious enough to suppose that for their own amusement the Greek gods are playing chess with our shrubberies.

If I'd been more organised, more focused, worked smarter not harder I'm sure I'd have much more done with the same free time, but that would need someone who isn't me.

The big chunks of metal that needed to arrive have. A shaping amplifier to test the preamps with and a NIM bin (glorified power supply) along with a few bits and pieces I should have bought years ago like a temperature controlled soldering iron. A flurry of components for the 2 cheaper versions of the preamps and the very clever forward biased design were also rapidly ordered and have arrived. I forgot to order any metal project boxes, so light and EM shielding are about to be a problem. Getting the shaping amplifier turned out to be more eventful than usual when the the parcel company that picked up the package from the plane put their stickers on top of the address and then couldn't work out who to sent it to. That isn't one of the 3 either. The amplifier is a little less flexible than I wanted, when buying off ebay I failed to notice the difference between shaping time and peaking time, but it's probably still the best from what was available and since I'll be replacing that with an open source design anyway it shouldn't matter.

One potential mistake is that when choosing the package for the max op amps I went for the 6 pin version thinking it would be easier to solder than the 8 pin version not realising that the 6 pins were SOT23-6's and rather smaller than a SOIC-8. Since I can't get the board design finished, exposed and etched before the July 11 deadline, in 19mins as I finish this log, I may simply order the SOICs and use the SOTs when I have a professionally made PCB.

There is currently no github for the design, but when I have some trial designs fit to be etched that is where they will go. I'll also need to finalise an open source licence. Right now I need to put together the parts I have in lots of different ways and see what combination works and works best, then I can move forward.