Ideally we were after some 10k digital pots that could handle up to 9v (to try out some digital effects pedals) but the nearest we could find were 20k, up to 16v (most digital potentiometers run up to 5v and we've heard some bad things about using 5v digitpots with a 9v supply). 20k instead of 10k is fine, we'll just use half of the available range (so we'll have 128 steps instead of 256 to play with). All this would be fine, except the chips themselves are teeny-tiny little things! So we had to make up some breakout boards:
Soic to Dip 14pin
These we easy enough to toner transfer (using a laminator, not a household iron) but a bugger to etch! The traces are a tiny 0.25mm so over-etching/under-cutting was a bit of a problem. From four boards (we only made up half of the boards in the design) only one was good enough to use without any doctoring!
Using solder paste and a fine-tipped soldering iron (and some blue-tac to hold everything in place while soldering) we got this little chip stuck down and tested in a few minutes. Sadly it was then too late for any testing, so we'll just have to get this hooked up and tried out some time soon...
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