Now, don’t tell me you’ve seen this one!..

After a long hiatus, I wanted to get back to electronics for a while. Finish dmx-dimmer and all. For warm-up, I decided to put together a CatNip kit that miceuz gave me.

A few sloppy minutes later I was de-soldering one side of a TQFP package (ARM chip), which was placed on a bed of SMD paste and slipped a bit. It was all going well, then a trace flaked off the board. Oops.

No biggie, just solder in a thin wire. 0.1 mm will do just fine. It’s commonly available in the form of transformer refuse.

CatNip development board, with GPIO2.0 output connector wired-up directly to the microcontroller

I kept on soldering, listening to psytrance, minding my own business, when suddenly and for no apparent reason a 0603 resistor jumped right at me, and was gone the second after. Bad luck, it was 2 kΩ, and I didn't have any more of those on hand I was too lazy to look for one. I did have several 1 kΩ and a pin handy, so I hooked these up in series.

Two SMD resistors standing vertically, connected by a clipped-off pin

After having populated most of the board, I noticed one resistor was still missing. 150 Ω, wasn’t in the kit. For demo purpose only, I decided to connect several larger-value resistors in parallel.

Several SMD resistors stacked atop one another, dont get annoyed by the following line

What I did here, as you most probably see, is stack five 1 kΩ resistors atop one another. Could have gone with six, but this is just current limiting for a LED, so the same precise value is not strictly required.

Here’s the complete board before I rub it with acetone and glue the frankensteins:

Resulting board, with all three quirks visible

Does it work? Well, it powers up and enumerates as USB storage, so I guess it does. No way to be sure, got no toolchain.

To give some context, here’s a lamp’s-eye view.

Big-picture shot of the workspace

That thing with a black/yellow handle? Unregulated 40 W noname, stock tip, China Export certified. The iron I was using. A close-up…

Iron tip and SMD component comparison, a white smurf is seen lurking in the background over my Cortex

Why in the world?.. For fun mostly, so that I truly can.

Published February 02 2013 by rxdtxd