Wednesday, February 22, 2012

PCB, easy as 123!

At last! The printed circuit board that I designed has arrived for my fermentation chamber thermostat.  Actually, I received it just over a week ago but haven't had a chance to document it.  I was very happy to see a package from BatchPCB in the mail.  Even more so to find it contained a second bonus board (not sure why, but it will be nice to have another one if when I ruin the first one.)

As expected, I did realize some mistakes that I made (shocking... I know) in the design of the board .  I, for some reason, didn't allow access to the microcontroller chip for reprogramming purposes.  So I had to add another header on the board for that.   I did this by drilling small holes in the pattern of the header into the PCB. Then after placing the header into the holes, I soldered small stretches of 30 gauge wire between the desired contacts.  There's nothing like going at your new prized possession with some power tools to get the blood flowing!

I also decided that the placement of the LED's on the board were too high (with respect to the faceplate of the case), I resolved this issue by placing the headers and LED's onto the back side of the PCB and then installing the board face-down inside the case.  This moved the LED's further down on the faceplate.

So after performing all the necessary changes, I soldered the remainder of the components.  I still have to test out all of the connections before I can add power and start using troubleshooting it, but all the parts are there... and I'm pretty happy about it!  Here's what it looks like:

You can see the little blue "jumper" wires just below the chip that I added to connect the new ICP (In-Circuit Programmer) header (all of the headers are shown in the top pic, what used to be the backside of the board).  I took these pictures before I cleaned the excess flux off of the board, which makes the board look even more sloppy (it certainly doesn't need any extra help).  Flux is a chemical that aids in the soldering process, it cleans the corrosion off the metal connections and allows the liquid solder to cling to the pads and wires.  However, it leaves a sloppy and dirty looking board afterwards.  The good news is that it comes right off with a little rubbing alcohol.

You'll notice that two of the corners of the board have been beveled.  This is so I can slide the board as close to the edge of the case as possible without interfering with the screw holes for the lid of the case. I'll add another post soon of how everything fits in the case.


No comments:

Post a Comment