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76  Forum 2005-2010 (read only) / News / Re: Open source Project / Hardware on: August 17, 2007, 09:03:04 pm
I have a curious love it / hate it relationship with opensource projects. Take open office which Ive used for a while now. Its great for a free program and means I dont have to support an evil empire but there are many things that bug the crap out of me about it. It suffers from featuritis.... too many chiefs syndrome.

I like how currently there are multiple arduino clones popping up by well motivated individuals seeking to carve out niche applications using alternate main boards. These are however individually driven projects. To me the best part of the openness is the latitude for all these fringe type projects to flourish.... This includes not only the hardware but software and documentation as well. Whether anything from these alt sources ever become incorporated into the main project ultimately depends on how successful the smaller projects become and how motivated the individual.

I respect the foundations need to rein in a little and retain some control over the core concepts of the main Arduino project while leaving the rest of us free to run away with stuff. Keep the lid on the core Arduino if nothing else because they have to support it.

Compare the Arduino to the Basic Stamp... in its first 10 years the BS had 3 million units in circulation. Thats with extremely centralized design, support and distribution teams. It must be intimidating for the foundation, now with 10k out the gate, to even consider 1 million! Anyway, I really support what Massimo, David, Dave, Tom, et al have done up to know and am not sure I see a compelling reason to change it.

Ill stop rambling,
Brian
77  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Pin as GND on: July 28, 2008, 04:49:48 pm
Absolutely, taking the pin low does it. Just dont hook anything greater that 40mA to that pin or else the magic smoke comes out and its hard to put back in.  smiley-wink  And you shouldnt put any inductive loads on it, ie motor or something with a magnet. But yes for an led or a sensor you can absolutely use a pin as gnd.

Brian
78  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Shield or standalone board? on: May 06, 2008, 11:45:43 am
This is the type of thing I usually do. I should post images sometime, but Ive made a couple Arduino based boards that have a couple ULN2003 or ULN2803s to fire off 16 solenoids. I can make a fairly small pcb with the basic stuff needed for the arduino and add the darlingtons and some pin headers and it is ultimately a whole lot cheaper than buying an arduino+shield+parts. I usually dont even include the ISP as I just program the chip in the arduino board and pull it out and put it into the new carrier board. (Now that I have a programmer that will all change....) Ive been using some really nice, stable and clean 5v switching power supplies for my work so this means the only thing that is really needed on the board is the avr, xtal, caps, and a power plug!

Cheers,
B
79  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Deployment strategy on: May 01, 2008, 10:54:53 pm
Yeah, I actually imagine SMT parts will make home etching more reasonable in the future. Drilling all those holes was such a drag conventionally. With pre-sensitized pcbs, all you have to do is print out your art on a transparency, slap it on the board, shine a bright light on it, develop and etch.

No, Oracle it was not a rant. Maybe a little flippant but whatever. Youre right I didnt acknowledge your comment about Olimex. Thing about them, is that its 24EUR for a ~6"x4" single sided panel with a maximum of 4 pieces per panel. That works out to almost 40USD or $1.6 per inch. Work that out in BatchPCB prices thats about $60, but you also get double side pcbs, double soldermask, and double sided silkscreen. Olimex is also pretty picky/limited about drill sizes where BatchPCB works with anything over 20mil diameter.

The $100 I "imagined" is for Gold Phoenix (ultimately the board house BatchPCB uses) which is more like $90 for 100sq in panel. This is double sided, double solder mask, and they route as many boards as you have for free. An extra $30 means you can have up to 6 different designs that they will panelize for you.

Anyway, the whole point of this was just to let the original poster know that fabricating nifty production quality boards wasnt entirely out of reach. That was all. And depending on the deployment, ie if there were multiples needed or this was some sort of commercial application, a pro level pcb might be worth the extra work (to learn Eagle) and expense. Okay, thats all I wanted to say.

Cheers,
Brian
80  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Deployment strategy on: April 30, 2008, 09:12:22 pm
Really?! Im not going to blow a hundred bucks on a whole batch of a single board that may or may not work and then have to go through the hassle of liquidating all the ones I dont use. Look, its your preference.

If Ive got 2 or 3 weeks to play with I would rather spend the 30 minutes some evening to whip up a little board for something in Eagle, zip it over to sparkfun, and when it comes back, happily put together a nice professional board in just a few minutes. The alternative is hassling with perf boards, making all the jumper wires (Ive always hated stripping wire... :smiley), and then spending the rest of the afternoon troubleshooting some errant solder bridge. Plus, Ive always felt anything Ive ever put on a perf board just seems so kludged together and altogether uncool.

When I consider what my time is worth, and the fact that I have very little of it, it makes sense to effectively have someone else do it. $25 + an hour or two work for some standalone board is a bargain compared to what, maybe a day or two's worth of work? What do you charge by the hour?

Anyway, the added benefit is that whatever I do in Eagle is repeatable, if I, or someone else, find themselves needing a similar solution to one that Ive already drawn up. This way I use sparkfun as a cheaper prototype and then I take the design to Gold Phoenix when I need a larger batch done. Id rather spend little and wait awhile just to know the design works before having a 100sq in coaster.

But honestly, YMMV. Just saying that for anything smaller than about 5"x7" batchpcb makes a lot of sense and is in fact a good alternative for final, professional designs.

Cheers,
Brian
81  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Deployment strategy on: April 29, 2008, 07:58:00 pm
The 10 board minimum doesnt really apply with some places like http://BatchPCB.com, if youre willing to wait. Theres a 10$ minimum and $2.50 per sq in so for small simple boards its not that bad to pay something like $15 to avoid the hassle of wiring perf boards. I cant tell you how much I despise wiring perf boards or hand-etching my own pcbs! Yeah itll take a week to get through the learning curve of Eagle but once you know it, its like riding a bicycle. So I guess I would suggest if this is a one off thing that just needs to be done quickly, it's not too bad to wire up a single perf board. But if this is something you might be doing again in the future and you have the time, I would suggest looking into making your own pcbs.

-B
82  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Larger Arduino projects on: April 11, 2008, 09:54:06 pm
Im a little late to this but I would like throw in a little.

First I really like the idea of a small accelerometer board with the same format as the blink-m. Using the sparkfun example there is absolutely no reason why these couldnt be produced for around $20 or so depending on whether the levels need to be shifted or not and what extra hardware is needed. (I also agree hacking the nunchuck is just in-elegant and wasteful.) The surface mount is simply not a problem when you manufacture boards yourself using the famed laser stencil/skillet method which is how every single board sparkfun sells in made. This method is simple and fast for reasonable sized batches of boards. Ive been too insanely occupied recently but I hope to introduce a new project that will use this fabrication method within the next couple of months.

Anyway, I am very much the hardware guy and if you need someone to manufacture something like this I might be able to help. But what would really make something like this shine is the supporting libraries also like the blink-m. And here I think is also a rub with the open hardware movt... not only do you have to get a bunch of folks to agree on the same tenants of hardware design, there's got to be those folks who will also get the software to work too. So, if there is enough interest in a 3axis uShield maybe that should be spun off as another topic for discussion and collaboration.

As I was thinking about this, a never ending string of stacking uShields could get a little tricky amp wise. Please correct me if Im wrong, but the blink-m uses two of the arduino (analog) pins as source for 5v and ground. This will only be good for 40mA correct? Stacking them is an open invite for some dead i/o pins if you ask me. Much beter to have the convenience of sticking on a little piece of kit that gives some functionality (such as a bad ass blinky light *OR* 3axis sensor, etc) and when you need the kitchen sink you can whip up the breadboard with the appropriate wiring. The trade off of convenience versus full functionality rather than trying to be the be all end all.

Finally, I would just like to say that I ABSOLUTELY love the chaos that happens with the Free/Arduino development. Its like a scene from the Smurfs, where the sun is out, the grass is green, and the butterflies lazily fly by when you are first introduced to this cute little blue guy that promises fully web enabled wine racks or blenders that speak to their owners. Then you pull back the curtains just a little bit and theres all this stuff being made, developed, proposed, and so on. Its like going to your first punk show in the 80s and having the biggest WTF moment of your life. Tod had been talking about 'smart leds' for a couple years and then one day out of the blue (to most of us) the happy arduino has a new blinky friend. Yeah its of lot of work and we all have our reasons for doing it but this chaotic development is downright fun if you ask me. Sure there could be more coalescing amongst some of us as we develop new things but I am very happy with this convoluted, prismatic, and even sometimes problematic landscape that has sprouted up around this platform. And that to me is an advantage of the open hardware movement and I applaud the foundation for their work and foresight to allow that to happen as well as the indie makers that in part made things happen anyway.

Cheers,
Brian
83  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: soldering pen on: November 20, 2007, 12:31:33 pm
Hakko is a Japanese product and of the highest quality, and extremely xpensive. The Circuit Specialists version is essentially a counterfeit soldering iron manufactured in china made to look like the Hakko. Whoever makes it will slap anyone's label on it too because they dont really care. Mine worked okay for about a year or two but I never really did like it. I just bought a Weller WES51 and the quality difference between those two irons is huge. The Weller is worth every bit of the extra cost. The amount of time I wasted waiting on the counterfeit to warm back up or just trying to hold it right so it would work was such a pain.

For cheaper pencil types, Jameco carries an Xcelite(?) brand that my students have had some success with. They even make a variable temp one too. Something to look at.

brian
84  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Project safety:  Fire?  Too paranoid on: June 29, 2007, 12:11:48 pm
Not to give you any more options BUT ( smiley-wink) Im a big fan of MOSFETs personally. They are fast enough that if you were to choose to do some PWM to slow the fans down (to make them quieter) at a later point you could. Here's a schematic that would work for you:
http://www.csulb.edu/~bevans2/schematics/mosfet.jpg
You would want diodes as shown for back-emf protection, the fans are 'noisey' like that. But with its higher current you could easily run all of the fans off a single MOSFET. The fans would be wired in parallel, or all the reds connect together and all the blacks connect together, with the reds going to the +9v on the arduino and the blacks going to the 'drain' pin of the 'FET. (Keeping in mind the diode has to go across the + & - sides of the fan.) So yes, you could use the 9v pin on the arduino, since it is really just a pass through, whatever goes in to the plug is what comes out there. (ie If you were to use a 12v supply it would be 12v at that pin instead of 9.) Otherwise regarding safety, use a good regulated switching power supply (my preference) and nothing should go wrong.
BW
85  Forum 2005-2010 (read only) / Bar Sport / Re: Book Recommendation on: March 25, 2008, 06:18:35 pm
Right, MTT is really great, I imagine, when one has a pair of xbee or bluetooth radios that need to, well, talk. I myself have not needed these technologies but once I do, MTT will be one of the first references I turn too. Yes, there seems to be a lot of 'fluff' like the pseudo project examples that can be tricky to wade through. At least the software side of things is all arduprocessing.

Phys Comp is great for the beginner needing to hook up things like vregs or switches for the first time. But it is rather sad that it was written seconds before Arduino's time. The overall concepts of the software are ok but the specifics just dont apply and really get in the way.... Once you get used to programming in arduprocessing basic is just arcane. (Edsger Dykstra was right....)

I would suggest looking at MTT and see how you get along with the book. If you like it but it just starts out a little too 'high' and you need some more basics pick up Phys Comp. If you really need basics, like 'what is an electron?' kind of basic, pick up Mimms the III 'Getting Started in Electronics.' While written before people like us ever thought of using a microcontroller it has some good circuit stuff except for the adherence to electron flow as the rule of god (after all these years I still havent recovered from thinking about electron flow....).

Cheers,
Brian
86  Forum 2005-2010 (read only) / Bar Sport / Re: Ambient Orb style casings on: July 14, 2008, 07:58:06 pm
Get some translucent Sculpey (polymer clay) and make your own! Its kinda translucent milky white in color, you bake it in the oven to make it harden. Once cured it can be machined (drill and tapped for instance) and/or polished to make more translucent. It works really well as a diffuser for LEDs.

-B
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