I'm in the process of printing my own Diecimila board and sourcing components but ive run into a few problems. In the Diecimila eagle schematic and the pdf schematic it shows there being 2 voltage regs, but in the board layout they on top of each other. Like on the same side on top of each other. So am I somehow an idiot or am i the 1st person to run into this problem? And if theres only supposed to be 1 voltage reg which would make sense, which one is it? Also I wanted to know what inductor im supposed to be using, all thats shown is 500mA. And also what type diode for D1 and what specs? And one last thing, are all those vias surrounding the voltage reg necessary? Theres like 6 of them and only 1 is over the dotted VCC lines surrounding it. I was going to pop in a smd dc jack but i have to move the reg(s) over a bit and make some space. Ok last question i promise, Theres all those dotted traces surrounding the board which i guess are GND but are they used and they the heck when i apply ratsnest the board is completely covered with checkerboard traces?
Thanks a lot if you can somehow manage to field all those questions.
You can, I think, use either regulator.
The checkerboard traces are a ground plane that should reduce noise in the circuit.
The diode can be any rectifier above 1A/20V. Just about every rectifier is rated higher than that.
The vias are there to pass heat from the regulator side to the gorund plane on the other side.
I believe there are two regulators for production reasons- better to have two sets of pads available, so if you are out of one type of reg the other can be used.
D
Thanks a lot to both of you. I've come along way since that question and I guess the only thing remains is the values of that inductor. Schematic says 500mA, and I've seen another version of a board running with a 10uF, and I'm pretty sure I read something in a thread about a 33uH. Also the schematic says its a footprint for a 'L1812' package, so I guess i just need the proper uH and the Mhz if they matter.
I'd be happy to share the modified revision of the board i've done, it basically just adds a SMD dc jack, smd mini-usb b jack, moves the one 8 pin i/o set over 0.05" to make a clean 0.1" spacing so it can be popped in a breadboard or protoboard. And finally, I went through and changed all the traces for through hole components to come in contact on the bottom of the board so crazy soldering methods nor through hole via plating aren't required.
If anyone happens to think of any annoyances they wish would be changed, please let me know. I only have a limited knowledge of these boards so I don't know all their ins and outs yet so i don't know everything that ought to be changed. thanks a lot.
I guess the only thing remains is the values of that inductor. Schematic says 500mA, and I've seen another version of a board running with a 10uF, and I'm pretty sure I read something in a thread about a 33uH. Also the schematic says its a footprint for a 'L1812' package
I don't think there are any inductors in the diecimila; are you talking about the component near the USB connector labeled "F1" ? That's a PTC Self-resetting FUSE. Like This digikey part. It's designed to prevent your computer from resetting when you accidentally short out the power on the ardunio, if your computer is so lame as to not include any of its own protection. On the boards I've built from scratch, I usually replace it with a bit of wire (and one of the "features" I added to some of the later Freeduino boards was a couple of extra vias in the middle of the fuse pads to make that wire easier to install...)
Thank you so much Westfw! I'm not sure how i got it into my head that it was an inductor considering it was labeled F1. I guess i might have been comparing the parts list to other models. Anyways thanks again, now i can finally get this parts list ordered today. Also if you happen to know what type (schotkey, zener etc) of diode that should be and reasonable specs for it, i'd appreciate it
I've been using 1n4004 diodes (1A, 400V); they're just what I happen to have on-hand. According to digikey, they don't come in the correct package, though (I've been using TH parts with their leads bent around and soldered to the pads. Eww!) Anything "about 1A, 50V or greater" should work fine (but the SMB package in the cad files seems rare, in the US, anyway...)
I grabbed a 1000V reverse, 30Amp surge, 1Amp forward, 1.1V forward Rectifier (link below). I reallly hope that will work. Its been a long time since i had digital circuits courses and im not 100% sure if a rectifier will work in this situation. If you think that diode below wont work, please let me know ASAP because a friend is placing a mouser order this week and he can grab me a proper one if needed. Thanks again for all the help.
Looks pretty identical to a 1n4007; it should work fine.
I'm not sure how i got it into my head that it was an inductor considering it was labeled F1. I guess i might have been comparing the parts list to other models.
You might have been thinking of the inductor used on some other boards for (I think) ADC noise reduction purposes.
--Phil.
FTDI also recommends a ferrite bead in the USB power lines, and this is present in some of the Freeduino schematics (and I think on the solarbotics freeduino board.)