Sunday, January 25, 2009

Clean Power

As part of my guitar effects house-cleaning I thought I would build a real 9VDC power supply rather than the mish-mash of batteries and hacked up wall wart that I use now. I also wanted to learn Eagle as it is always touted as the best, free CAD package out there for hobby electronics. I decided to start with this circuit for an adjustable power supply from Tonepad. Tonepad is great, but I think a lot of their layouts aren't the greatest since they don't try to minimize the amount of copper you must etch off of the copper-clad board. As a result, etching takes longer and you end up using more ferric chloride. This isn't really a concern, but I figured I could come up with an more optimal layout, and basically used this as an excuse to learn Eagle. I've never actually designed a single layer PCB before (my previous designs have been double-layer boards, ordered online from ExpressPCB), and never realized how difficult it was to route things given the single-layer design constraint. As a result, it took me much longer than I expected. I ended up with this layout:

I think it turned out alright, and I learned a lot in the process. Eagle is definitely much harder to use than ExpressPCB, but it has quite a bit more functionality (most of which I don't know how to use).

I also decided to experiment with Sharon's scrapbooking machine while I was at it. Instead of trying the usual toner-transfer method of etching the PCB, I thought I would try cutting the mask out of vinyl and etching the board that way. I loaded up her Klic-n-Kut, and cut out the layout which I had exported from Eagle.

I then applied the mask to the copper clad board. If you look really close you will see that the mask produced by Sharon's machine actually isn't all that great. I am on the very edge of the capability of her machine in terms of size. Basically, the size of the pattern I am trying to cut is so small, the machine can't produce it (the knife works by pivoting around a slightly off-center pivot point, which is about the size of one of the corners in my layout). There may be various ways around this, but I may just end up going back to the toner-transfer method for future layouts.

After about 15 minutes in ferric chloride, I had a PCB for my power supply.

All that was left was to drill the PCB and mount the components. After a bit of smoke (I soldered in one of the diodes backwards...oops!), the result was a working 9VDC power supply for my future guitar effects projects.

From Effects Pedals

Lots of Snow!

We got an email from Michelle the other day saying it was snowing in Scotland. That's nothing compared to the mass of white stuff we've received over the past week or so. Check out these pictures I took a week ago!

From Winter 2009

This was as the snow was still falling, and we got quite a bit more overnight. We had a bit of a warm spell during the week and a bunch of snow melted, but we still have a good amount lying around. To be honest I'm pretty sick of winter right now and can't wait for spring to arrive!

Thursday, January 15, 2009

Validating Archive Contents With Ant

Have you ever wanted a quick way of validating the contents of an archive as part of your Ant build? I'm sure there are many ways to accomplish this, the most straightforward being to inflate it to a temporary directory, but yesterday I crafted up this little nugget to validate an archive in-place and it seems to work great. And the best part is there's no messy cleanup needed afterwards!

<!-- Compute the difference of the actual JAR and the expected zip entries -->
<resources id="artifact.set.discrepancies">
<!-- Create a resource set from the actual archive -->
<zipfileset src="${}/some_archive.jar" includes="**/*" />
<!-- Create a resource set of expected items -->
<zipentry archive="${}/some_archive.jar" name="afile.ext"/>
<zipentry archive="${}/some_archive.jar" name="anotherfile.ext"/>
<zipentry archive="${}/some_archive.jar" name="a/path/to/afile.ext"/>
<zipentry archive="${}/some_archive.jar" name="some/other/path/to/afile.ext"/>
<zipentry archive="${}/some_archive.jar" name="META-INF/MANIFEST.MF"/>
<pathconvert property="set.difference" refid="artifact.set.discrepancies" />
<condition property="artifacts.verified">
<resourcecount count="0" when="eq" refid="artifact.set.discrepancies" />
<!-- Fail if any differences are found -->
<fail unless="artifacts.verified"
message="The following artifacts were not expected: ${set.difference}" />

Note: I believe a minimum version of Ant 1.7 is required for the resources stuff to work.

Friday, January 2, 2009

Tonelab For Sale

I'm selling my VOX Tonelab SE in an effort to minimize my guitar rig in 2009. If anyone reading this knows anyone who may be interested, feel free to contact me. The Kijiji ad is here.

I think I'll try to round out my sound with a few more home-brew pedals. I have a Tube Screamer and a Ross Compressor built. I'll need to find some good designs for a chorus and delay pedal and perhaps a flanger and a simple reverb unit. I wonder what's involved in building a tuner as well. Hmm... Tonepad here I come.