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31  Using Arduino / General Electronics / Re: Newbie question on designing your own 'board' instead of using wires on: January 05, 2013, 06:53:37 pm
Bear in mind that DipTrace modifies the security settings of the Documents folder.  In my opinion, the behaviour borders on that of a virus.
In what way does it do this?  Not that I think it affects me (it creates its own Documents folder on a Mac), but it seems rather odd...
32  Using Arduino / General Electronics / Re: Where I got my PCBs made on: January 03, 2013, 07:30:24 pm
Just received an order from Seeed myself, 21 days from placing the order to receiving the boards in North Carolina with the cheapest shipping option.  The boards look good, and they gave me 12 rather than the 10 I ordered.  There's no need to add the order number to your Gerbers any more, nor to e-mail them in--they now let you upload them on their web site.
33  Using Arduino / General Electronics / Re: Newbie question on designing your own 'board' instead of using wires on: January 03, 2013, 07:26:47 pm
Another option is DIPTrace.  Like Eagle, there's a limited free version available.  Unlike Eagle, though, the limitation is based on number of pins (300 or 500 pins in the free version), not board size.  Versions are available for Windows and Mac, though the Mac version is just running in WINE.  It works, but it's not very Mac-like.  There's also a detailed PDF tutorial you can download/print.  http://www.diptrace.com/ for more info.
34  Using Arduino / Project Guidance / Re: First Project with the Arduino - Sous Vide - Dimmer / Heater on: January 03, 2013, 02:51:47 pm
So is it important to leave the heater on for a period of time to make it effective? Like a 1/2 a second or something? Since I don't have a zero-cross detection shouldn't I be leaving it on for several cycles. Have like a minimum on time?
If you just buy an off-the-shelf PID temperature controller (like http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=3), as is pretty common for DIY sous vide cookers (and what I did), it will do just what you're suggesting.  You can adjust the time base, but it defaults to 2 seconds.  So, 10% power would be 0.2 sec on and 1.8 sec off, 50% would be 1 sec on and 1 sec off, etc.  An SSR is the most common device used to switch the heater on and off, as a mechanical relay would quickly wear out from the on/off cycles.  Properly tuned, and with an appropriate temperature sensor, these can hold temperature to within a few tenths of a degree without a problem.
35  Using Arduino / Project Guidance / Re: Ham Radio project - Arduino and MFJ TNC on: January 02, 2013, 08:20:25 am
The serial output on an Arduino doesn't match the RS-232 voltage levels.  To do the conversion, you can get a MAX232 module through eBay for a few dollars.
36  Using Arduino / Programming Questions / Re: RTCLib parsing on: December 09, 2012, 08:04:40 pm
Thanks Nick.  So I've used sprintf, but am unclear how to get the last character.
This is what I have so far.  How do I get the last character out ?
Code:
  n =sprintf (buffer, "%d", a);
You could instead do this:
Code:
sprintf(buffer,"%.2d",a);
...then you'd know that buffer contained two digits (prefixed with 0 if a < 10).  buffer[0] is the first digit, and buffer[1] is the second.  And, as mentioned, you can do that with the the rest of the time elements as well, even putting them all into the same buffer:
Code:
sprintf(buffer,"%.2d%.2d%.2d",now.hour(), now.minute(), now.second());
I see that guix's example uses %02d while mine uses %.2d; I'm honestly not sure what the difference is between these two.
37  Using Arduino / General Electronics / Re: Panelizing EAGLE files? on: December 09, 2012, 07:19:38 am
Not sure where I was looking at Itead, but clearly not at the right page.  Even so, though, the $/in^2 is clearly much less for the 10x10 than the 5x10.

Copy and paste in Eagle gave me two problems: (1) a second copy of my board would be outside the 8x10 cm working area for the free version, and (2) it will renumber all the components, which isn't good when I'm planning on distributing the boards.  There's a ULP that comes with Eagle which I understand addresses the second issue, but not the first.

In any event, I found the (or at least a) solution in the DorkBotPDX .CAM file.  Just add this section to the end of your .CAM file:
Code:
[Sec_11]
Name[C]="Board Outline"
Name[en]="Board Outline"
Prompt[C]=""
Prompt[en]=""
Device="GERBER_RS274X"
Wheel=".whl"
Rack=""
Scale=1
Output="%N.BOR"
Flags="0 0 0 1 0 1 1"
Emulate="0"
Offset="0.0mil 0.0mil"
Sheet=1
Tolerance="0 0 0 0 0 0"
Pen="0.0mil 0"
Page="12000.0mil 8000.0mil"
Layers=" 20"
Colors=" 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 6 6 4 8 8 8 8 8 8 8 8 8 8 8 8 8 4 4 1 1 1 1 3 3 1 2 6 8 8 5 8 8 8 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4 2 4 3 6 6 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0"

Then, at the beginning, add a line that says "Section=Sec_11".  Having done that, gerbmerge works fine.  It seems like a pretty powerful tool, but it has a bit of a learning curve.  It'd be great if there were a GUI front-end for it.
38  Using Arduino / General Electronics / Re: Panelizing EAGLE files? on: December 08, 2012, 06:39:51 am
Iteadstudio and Seeedstudio are the same price for 5x10 as for 10x10--it's $25 for 10 boards in either size from either place.  Getting twice the boards for the same price seems good to me, if all I have to do is cut them apart.  Of course, the preliminary step of getting the files ready to place the order seems to be more involved than I'd anticipated...
39  Using Arduino / General Electronics / Panelizing EAGLE files? on: December 07, 2012, 06:43:07 pm
No doubt this isn't the best place for this question, but it seems reasonably on-topic.  I have a PCB design that measures 3.35 x 1.65", and I'd like to arrange this two-up to have boards made from SeeedStudio (since 5x10 cm costs the same as 10x10 cm).  I can't directly do this in Eagle since I'm using the free version, which is limited to a 8 x 10 cm board size.

I've found a write-up at Instructables (www.instructables.com/id/Panelizing-PCBs-for-Seeed-Using-Eagle-Free-Light/) which recommends, and gives instructions for, using gerbmerge (http://ruggedcircuits.com/gerbmerge/) to panelize the Gerber files.  I'm running into a problem, though: gerbmerge seems to require a .BOR file, and Seeed's .CAM file for Eagle doesn't seem to generate a .BOR file for the Board Outline.

Being a relative newbie to Eagle, and a complete newbie to gerbmerge, I'm kind of stuck here.  How do I get the .BOR file generated, or can I tell gerbmerge to skip it?  Or is there another, better option to do what I'm looking for?
40  Using Arduino / General Electronics / Re: Changing ceramic capacitors to electrolytic on: December 03, 2012, 06:53:13 am
I'd think the AC source indicated would be a problem for an electrolytic cap.
41  Using Arduino / General Electronics / Re: Help me choose a DC boost converter IC on: December 02, 2012, 11:11:41 pm
I'd get a pre-built one off ebay: http://www.ebay.com/sch/i.html?_nkw=5v+dc+boost
Trying to keep everything on one (small-ish) PCB, so I don't really have room additional modules.  That would make the job easier, though.
42  Using Arduino / General Electronics / Re: Help me choose a DC boost converter IC on: December 01, 2012, 04:27:50 pm
Fortunately, the NCP1402 data sheet calls out a particular inductor, which is easily and inexpensively available.  Likewise, they give specs for the output cap which should make it easy to comply.
43  Using Arduino / General Electronics / Help me choose a DC boost converter IC on: December 01, 2012, 02:36:44 pm
I'm working on a Teensy-based project that I want to power with a couple of AA batteries, so I'm going to need to use a step-up circuit, and looking for an IC to handle it.  Here's what I need to do with it:

  • Input of 2 AA batteries, output of 5V DC
  • Average load of ~70 mA, peak about 135
  • Surface mount, but not too small--the MAX1674 with .5mm pin pitch was just too small for me to hand-solder
  • Minimal additional parts count
  • Cheap, if possible
  • Efficiency would be nice, but this isn't intended for constant use--10-15 minutes at a time at the most, so battery life shouldn't be a big issue

I'm looking at the NCP1402, which seems to meet all these requirements, but is there another choice that would be better?
44  Using Arduino / Project Guidance / Re: Raspberry Pi mini computer? on: November 28, 2012, 06:25:02 pm
What a change there's been to the meaning of "mini computer"...
45  Using Arduino / Storage / Re: Power consumption to write to SD card? on: November 25, 2012, 08:19:08 am
Sounds like a job for the min/max mode on the DMM, and maybe checking it out with a couple of different uSD cards.
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