The thing that I most like about dabbling in electronics is that I’ve been able to create circuit boards at a resolution that should be very difficult to do at home.  In fact, I’ve managed to do so with relative consistency.  Despite my success, I’m not entirely thrilled with the lithographic process.  It requires a lot of discipline (which I have not got) and chemicals.  If a board doesn’t turn out, there are a myriad of possible reasons.  There may have been a fingerprint on the mask, the etchant may not have been up to temperature, the developer could be nearing the end of its useful life, I...

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I’ve been spending a lot of time on CNC lately.  Quite a while ago I wrote about mounting my Olimex MT-128 circuit board in a plastic box to make it easy to take with me places.  That was a good idea, and it certainly kept the cat away from my projects.  Unfortunately, it also made it quite difficult for me to work on a project.  The problem was in getting to the back of the circuit board to plug in programming headers, connect to pins, etc.  For some reason it took a while for me to realize the neatest, cleanest solution: mount the experiment board to the top of the pencil box.  Genius!

 

Not so fast, though.  I tried that once before and it was mostly a failure.  Trying to hack up a flimsy plastic box with any precision is no easy task.  This time, though, I was armed with a lot of recent CNC experience.  I opened up TurboCAD and drew up the dimensions (or so...

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Recently I decided that it was high time I tried to reflow a circuit board.  Previously I had been waiting to create a circuit to control the toaster oven, but I thought “Hey, what if I just control the oven by hand.  That should work out,right?”





Unfortunately, the heating profile was pretty lousy. ...

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This week I decided that it was high time I got back into some projects.  My next goal is to create another robot.  This one will be quite a bit more intelligent, though.  The robot will be controlled by a PC (probably a Windows laptop, although I have several mini-ITX options as well).  Most laptops no longer have serial ports, so the robot will need to be controlled via USB.  Although it won’t suffice for later revisions AT90USB647 seems like a good choice for right now.  It has six 16 bit PWM channels, and four 8 bit channels.  The device supports USB, and serial interfaces.  Perhaps best of all, it supports...

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I have good news, and an apology.  The good news is that since DotNetNuke (my hosting software) now supports the MetaWebLog API, I can dump WordPress (my old blogging software).  More good news is that I was able to bring over most of my posts, with one caveat.

The bad news is that the formatting is messed up...so you might not see bolding and paragraph breaks.  Really, a pretty small price to pay!

I've been playing with an ATNGW100 lately. The idea is to use the NGW100 to communicate with a peripheral board remotely using an XBee wireless module. Of course, the XBee headers are a non-standard header size. I've got adapter boards, but they have an Octal buffer\driver on them. If I were using a Max232 chip, it would dump low voltage out one side and high voltage out the other. I didn't want to risk the same from the Octal buffer\driver, so I whipped up an XBee adapter board. Naturally, it had 40 tiny holes. What a great chance to play with my mill for PCB drilling. At first, I tried drilling before etching. The idea was that I would lay the mask over the holes. Unfortunately, I filled the pads when I printed the mask...so the alignment wasn't so good. On the next two boards, I decided to drill them after...

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The drill pattern in the above piece of copper clad board is less than two inches on a side.  Probably about 1.75 inches.  You will notice that the holes are perfectly aligned, but there is no visible pattern on the board.  As I wrote previously, I intend to begin using my CNC mill to drill my circuit boards.  This is the first example that was drilled using my mill, and they were drilled without any manual intervention.  The mask from which the drill pattern came is shown below. If you're very detail oriented, you noticed that three holes are missing from the copper board.  This is because...

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Wow!  What an exciting couple of weeks.  Sure, most folks wont care about all the fantastic things I'm about to reveal, but at least I can count on Mom to read what I write, smile, and nod. The first thing I want to share is a pencil box that I modified to hold some of my projects.  I made holes in the side for plugging in the cables.  Now, projects can sit on my desk safely without fear of being molested by the cats when I'm not looking.  The MT128 board is attached using plastic concrete anchors from the hardware instead of "real" standoffs.  The other three boards are attached with double stick tape.  You'll notice that the board in the upper right hand corner is one of my home-brew AT90USB162 boards, being used as a UART bridge. By the way, yes, I know that putting my boards in a plastic box is like running around in a thunderstorm holding up a lightning rod...especially in the winter.  I'm considering some strategies for ESD dissipation, so if you have good advice, I'm listening! ...

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This evening, as soon as Evelyn was supposed to go to bed, I snuck off to the basement.  The 2560 circuit board has a lot of holes in it, so I cheated and drilled out only the holes I would need to get the board to power up for me.  There were seven vias and ten holes for the programming header.  There were also, of course, 100 very tiny pins to solder. As soon as I finished soldering everything together, I raced upstairs to plug the board into my computer.  As these things go, instant success is rare, so I wasn't surprised when the programmer failed to detect the board.  After rooting around with a multimeter, I found the problem.  This is a problem I noticed the last time I printed the board, but somehow I failed to remedy it.  The reset pin was not connected to the programming header. A friend called this afternoon to chastise me for not simply shipping the design off to a board house to have a professional board made.  You will notice my temporary "reset" wire, connected to the programmer.  This would also be the reason I have not shipped the board out to manufacturer yet.  Once I finished the design I'll have several professional boards printed....

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