If you’ve never gotten a printed circuit board (PCB) manufactured, it’s pretty daunting at first, but well worth the trouble—it’s exciting to get a stack of fresh, neat circuit boards of your own design in the mail, and a whole lot more fun than hand-soldering perfboard!

I use EAGLE to design my schematics and boards, and now that I’ve gotten used to its seemingly inscrutable interface, it’s quite fast and effective.  Here are some tips I’ve learned:

• Get Sparkfun’s library of common and useful parts, and check out their tutorial.  Drop the library in {Applications}/Eagle/lbr.
• If you’re using an external mouse, holding the center button down pans the layout—extremely useful, hard to live without!
• Get to know the names of the commands, like ‘add’, ‘group’, ‘move’; and remember that you can type the first couple of letters (‘gro’) instead of click the button, which is much faster usually.
• Moving groups is a bit of a pain; you first define the group by selecting it with the group tool, and then move it as a separate command.  You can right click and choose “Move Group” or Command (Ctrl on Windows)-Right Click.
• When you are moving a part, right-clicking rotates it.
• If you want to put a part on the bottom of your board instead of the top, just middle-click while moving it (or use the Mirror tool).
• When adding parts, if you want to search for something, put asterisks around it, like ‘*battery*’, or else you probably won’t find anything.
• Use Sparkfun’s CAM job to output all the files you need to get boards made.  When I go through Advanced Circuits, I need these files:
• .drd, .GBL, .GBO, .GBS, .GTL, .GTO, .GTP, .GTS
• If you only need 1 or 2 boards, Advanced Circuits offers a “Student Special” on Standard Spec boards for $33 each.  Just put “Student” in the comments box when you order.
• Another great way to get a few boards to test is with Barebones boards, which have no solder mask (the green coating) and no silkscreening.
• This has a slight danger of making it possible to accidentally bridge traces while soldering, but if you’re careful, it’s a good savings.
• When you get the boards, use a green scrub pad (a soft scouring pad) to get the traces nice and shiny.
• You can put text or graphics on a copper layer if you’ve got the room for it, which is a neat way of making up for the lack of silkscreening!
• I also found a great way to use vector images on your circuit board, which I used to put the Limina.Studio logo on my newest project.
• Got any other tips or ideas?  Post a comment and I’ll add them!

A few months ago I accidentally fried my Wii Sensor Bar (a misnomer as it does not contain sensors of any kind) by powering it with an unregulated 12V power supply—whoops. So instead of buying a new one, which I’m loath to do given the typical prices, I built a new one with some infrared LEDs, a regulated power supply and—yes—a piece of cardboard.

Just solder up each LED after a 220 ohm resistor in parallel with each other—not in series.  This can be done with two “rail” wires, one connecting the positive leads, one connecting the grounds.  Then connect the rails to a standard barrel power connector and plug in your power supply.  I also added a green LED for visible power feedback.  Enjoy!

Day 1 consisted of just plugging the Arduino in to see if it works and transmits properly.  Today, despite an incipient cold (wtf?), I made better headway into learning about the device.

After some initial tests blinking an LED, I decided to make a little sinusoidal pulse-width modulator and blink two LEDs:

Pulse-Width Modulation of LEDs

If you watch it you can see the LEDs blink faster and faster and then slower and slower (the avi’s framerate of ~15 of course interferes with this).  The relevant code is:

blinkFreq = ((sin((i * PI / 180))+1) / 2) * freqMod;
...
digitalWrite(ledPin, HIGH);
digitalWrite(ledPin2, LOW);
delay(blinkFreq / 2); 
digitalWrite(ledPin, LOW);
digitalWrite(ledPin2, HIGH);
delay(blinkFreq / 2);

where i is incremented in the Arduino loop and reset after 360.  I could have just used radians but then I’d be incrementing a float value or something so… meh.

I’m not sure if there’s a better or more logical PWM algorithm, I haven’t tried looking one up as this basically does the trick.