Final Destination

Well, not really--this isn't my last post (the first one was like all of a couple weeks ago), but there Is some progress involved. Actually, I'm on my last board at this point. YAY! Let's do a quick review of my summer thus far. I first started with the very simple (by now, this is literally a piece of cake, even though I was hyperventilating during that first week) preamp board:


There are a few changes since the last time, but everything is essentially the same. It is simply four (with another small one) circuits, mostly identical, running from four connectors in the center and out to the edges. Of the three boards, this one goes in the middle--it sits above the anode and below the TDC board, which is the following:


I finished this yesterday, a proud product of about three weeks' hard work. Main additions from last time are the reference designators, or the names of each of the parts. It wasn't too bad, just tedious rotating and resizing and moving each to fit next to its respective part. Compared to the preamp, this is probably a true test of what I learned. The preamp is just a tutorial if you look at this one. I think being able to do this board actually shows that I can do something, that I can use PADS and get some engineering done. Conceptually, this board was not that much harder than the first (probably even easier in that respect), but it was just a lot more tedious and complex in terms of structure. So I guess the TDC is just a natural extension of the preamp. Oh yeah, if you are curious as to how the actual parts look like on the board...


Looks a lot cooler, doesn't it? And the wires coming out of the back too--this all seems to make a lot more sense when you see it physically.

And finally, we come to the anode board. Here are some pics to get an idea of how it looks like:


It sure doesn't look anything like the other two boards. As you can see, it is Much simpler than the previous two in terms of parts and routing. In fact, there are only two layers on this board, and all the parts that you see on the top make up pretty much everything. The schematic for this is only one page, and it's just the same thing over and over, to be honest:


Why am I so apprehensive? Well, simple as it may be, the conceptual part is Much more difficult to appreciate. All the copper-plated portions of the board have to be shaped on PADS. The top side is a little easier, although the cutouts into the circle will probably be a bit strange. On the other hand, the back contains a skeleton of circles, as well as anodes (the many circular sectors) in between the radial copper lines, but not connected to the skeleton. This board is indeed unusual in many respects, and PADS was not, as far as I know, built to handle such things. My coworker (who has worked with PADS for a year) told me that this is beyond his domain. It's like going from Pre-Calculus to Calculus and then all of a sudden being rudely thrown into Linear Algebra.

At the very least, I do have some idea of how I'm going to approach it. It will be a lot more geometry and creativity on my part, such that I can brute-force PADS to do what I want it to do. More on that coming up, as I work through it. At the very least, my expectation is that it should take no longer than a week to do, 3 times faster than the TDC board. Here is what I did today. Same business--board outline, clean up schematic, create netlist, import parts.