Stokes' ProjBlog

Victory! January 26, 2008

…Or at least not a total defeat.

Generally, it came out fairly well — well enough to attempt etching. I prepped the board by scrubbing it down first with regular scouring powder (Comet) and a sponge, then with alcohol and paper towels. For the laser print, I used magazine paper again (actually, pages from the LEGO catalog that came with my giant LEGO blocks), attached to either side of the board by tiny pieces of masking tape. I placed the heated iron on top of the board for about 10-15 seconds before starting to iron it down, which I did much more lightly and quickly than before (maybe one minute per side), smoothing out from the center. Etching took about ten minutes.

(more…)

Almost there… January 23, 2008

Motor Controller Board toner transfer attempt #3: partial success.

Going back to the magazine pages improved things immensely. The paper adhered tightly, and as can be seen in the image below, the majority of the toner transferred successfully.

Despite this being much better than the previous attempt, however, the board is still unusable.

(more…)

Doing the unstuck January 21, 2008

Motor Controller Board toner transfer attempt #2: failed.

An oft-quoted definition of insanity is doing the same thing repeatedly and expecting a different result. I don’t think I’ve quite lost it yet, at least not completely, but I was perhaps a bit overly optimistic. I was hoping for a better outcome than my previous attempt; in hindsight, however, I realize I could have done a bit more to differentiate this try from the previous one.

A bit more, in this case, meaning anything at all.

(more…)

A non-sticky situation January 12, 2008

Last week, I finally got around to printing the new motor controller board. Since I did not have any usable glossy magazine pages as I’d used in my first toner-transfer attempt, I opted to use high-gloss inkjet paper.

It was a catastrophic failure.

Despite a myriad of toner-transfer articles on the web singing the praises of high-gloss inkjet paper, very little transferred to the copper-clad board at all. Surprisingly, the cheap, thin magazine/catalog paper worked much better. There were other differences, so I really can’t point at any single one as being the point of failure.
(more…)

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.

(more…)

‘The Motor Controller Project’ September 3, 2007

This project is actually sort of a sub-project; it will later be used to drive more interesting things.

This is my first attempt at an L298 H-Bridge motor driver board. It is based primarily on some sample schematics from the L298 data sheet; some inspiration was also gleaned from other similar projects available on-line. This will also be my first attempt at etching a PC board, which is a little daunting.

The design is fairly straightforward; it isn’t much more than a breakout board for the L298, plus the minimal handful of additional parts to support it. I’m going deliberately simple in order to keep it as generic as possible; I originally bought my L298 ICs with the intention of providing forward and reverse for a pair of standard DC motors, but it now looks like my first application will be driving a bipolar stepper motor.

(more…)