Stokes' ProjBlog

‘The LegoLCD Project’ December 23, 2007

Last month, I briefly mentioned the serial LCD I’d dug out of storage. I have a number of ideas for it, such as using it as the display for a Python-based MP3 player. Whatever I do with it, however, I need to put it into an enclosure.

A while back, I saw something interesting: the LEGO Quatro system. Whereas Duplo is twice the side of a standard LEGO brick, Quatro is twice the size of Duplo brick. It’s very clever: toddlers can be given Quatro bricks, then use them with Duplo bricks when they get older. The kids can then use the Duplo bricks with standard LEGO bricks when they get older still. In any case, some gargantuan LEGO bricks seemed perfect for some sort of project or another. I didn’t have any specific idea in mind when I bought them, but a pair of 2×4 bricks ended up being the perfect size for the serial LCD.

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A whole lotta diode. December 16, 2007

I received my order from Electronics Goldmine late last week. It contained, among other things, a couple of items for the Motor Controller Project: several 3″x4″ pieces of copper-clad board and twenty 1N5404 diodes (3A, 400V). I knew these were overkill, but I figured it was safer to err on the side of caution.

What I hadn’t figured was the physical size of the new diode. In my original board layout, I’d used 1N4004 diodes, only because they were what I had on-hand. The 1N5404 are more than twice the width and time-and-a-half longer than I’d planned. I tried cramming one onto my mockup of the board (a printed copy on cardboard) and failed ridiculously.

So: the board needed to be redesigned.

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Come up and see my etchings December 9, 2007

I finally got around to doing some PCB etching. For my first experimental attempt, I made some little carrier boards for an SMD IC: a M62364FP digital/analog converter, intended for the analog meter project.

It’s been more than a month since I did the toner-transfer with a clothes iron to the copper-clad board (some incredibly thin stuff I bought at the MIT Swapfest a while back), but I’ve been reluctant to break out the ferric chloride and do the actual etching. The transfer was only moderately successful; there was a small degree of smudging. I don’t think the paper moved; I may have used too much pressure and/or heat. The smudging would have been acceptable for a board with larger traces, but it was enough to short some of the board’s traces. I had tried to scrape away some toner with an X-Acto knife before the etching, but that was only moderately (if at all) successful. I may try scraping away the tiny shorts with a diamond-tipped stylus; I think I have one around, somewhere.

The etching took a remarkably long time. I’d pre-heated the ferric chloride by placing the bottle in a tub of warm water, and the ambient temperature was probably 65°F, but it took nearly 30 minutes to complete etching. I etched two, one after the other, and each took about the same length of time. I should have probably left it in even longer; it could have removed the shorts.

While this wasn’t the most successful attempt, it was my first try. I’m optimistic. Once I get some heavier copper-clad board, I’m going to try making the motor controller board. More board, along with some 3A diodes, is in the mail.