Journal Alioth's Journal: I hate making cables 3

I really, really detest making cables. I'd forgotten how awful a task it was, since I hadn't made one which you have to solder together for ages (I've used IDC for practically everything). But for the ALIAC-2 weather station, I needed 9 core cable for the temp/pressure/humidity box to run back to the CPU box, so that's ethernet patch cables out. I decided to make the nixie display box use the same 9 pin bayonet locking DIN plug and socket, because It Looks Right more than anything else (the nixie box only needs SPI signals, power and a data ready interrupt output. But it also needs to be shielded).

It took aaaaaages to make the bloody cable up. Soldering the wires into the DIN connector is a slow, fiddly job - even though I have proper tools these days and a helping hands thing. Then to compound the problem, I got the diode the wrong way around (after double checking it) on the socket on the CPU side. (The diode's there because the nixie box is a 5 volt SPI device, sharing the bus with a 3.3 volt SPI device. It accepts a 3.3 volt signal, but the output is still 5 volts - so the diode is just a simple level shifter, so the logic 1 is provided by a pull-up resistor, and logic 0 by the nixie box pulling down through the diode). Fortunately, I didn't kill the SCP1000 pressure sensor in the process... fortunately, its latch-up protection is good enough, so it seems.

First I thought it was because the signal going down 12 foot of cable was suffering too much cross talk, but the oscilloscope showed that at the data sampling points, crosstalk wasn't an issue (and the signal rise times/fall times were fine). It's when I checked the diode for a third time that I realised my mistake. D'oh.

As for the ABS box, for the next time I have to cut long straight lines in things I think I'll get one of those 2 axis vice things for the drill press. In fact, I've had a thought... a couple of stepper motors, a microcontroller, and a bit of code and I could have a poor man's milling machine for jobs like that :-)

Too many projects!