Alioth's Journal: [nixies] SPI board assembled

Well, the new nixie tube display is assembled, and I made a real pig's ear of it.

http://www.alioth.net/tmp/nixie-spi-board.jpg - showing temperature and dewpoint in celcius.
http://www.alioth.net/tmp/nixie-board.jpg - showing a test count, doing 200 counts per second (that's why the last two digits appear to be showing more than one number at once)

The PCB. It was by far the worst fabrication I've done, and it was only a single sided board. It went wrong right from the get-go - I slightly mis-measured the width of the tube sockets - but only ever so slightly. It wasn't noticable until I had soldered in the third socket and noticed it was slightly skewed. I had to shave a little off each socket to make the remainder fit.

Then making the board... the etching didn't go all that well - I missed a spot where the etch resist had come off (so there were about 4 opens). I also missed a couple of spots where the paper hadn't come off, leading to a couple of shorts. Then when it came to drilling, I managed to miss three or four of the holes. I also let the drill chuck touch the board, which took off a bit of copper, leading to another open. In short, it was a disaster. However, it was a recoverable disaster.

Electronically, it worked fine - so at least the electronic design seems to be OK. The board uses SPI so that a microcontroller or computer can send it data, and get data back (the white connector just right of bottom centre is so that a button pad with indicator lights can be connected). The only thing I've not been able to test is the decimal points - I have to disable the reset pin on the AVR to do that, since I need to use that pin as the decimal point output - which means I can no longer program it (without a special high voltage programmer, which I don't have) so that will be left to last.

I think I'm gonna have Olimex make the PCBs for the boards that other people are likely to see :-)