Wednesday, February 20, 2008
Extending the USB prototype board
The "different for a change" was actually not all that different. I cobbled an SN754410 quadruple half-H driver chip onto my working prototype USB board.
It's not exactly an elegant design, but it works. I'm really starting to hate these last few spools of solid core wire I bought from Potter's. The plastic insulation on the wire shrinks outrageously when I use it to connect strips. I didn't have nearly that kind of trouble with the wire from Radio Shack. Unfortunately, Radio Shack wire tends to come in two colours, orange and black, which is nice for All Hallow's Eve decorations, but not very useful for many other applications.
Anyway, I just finished a continuity and voltage check under power. I had one missing wire and one dry joint, both of which I fixed. I'll do the check over again in the morning after I've been awake a few hours to double check my work.
I've found that if I do wiring up one day followed by a first board check a few hours later with my multimeter and then a second check the next day before I start plugging in chips I save myself a lot of drama with chips crackling like distant gunfire and overheating voltage regulators. It only took me about 25 years to figure that out. :-s
I should be able to try to crank up one of the new stepper motors either tomorrow or Friday at this rate.
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