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Old 06-14-2008, 04:35 PM   #291 (permalink)
dcb
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Quote:
Originally Posted by ttoyoda View Post
I plan to use optoisolators.
That is a fine plan The supermid uses a couple transistors FYI. I started with the couple transistors approach but must have messed it up (it is more complicated to assemble than just a zener), and swapped in the zener and resistor, and it worked and so called it good.

After researching it a bit more (hint: we could use more researchers), I did see that some of the arduino crowd add a 12v regulator prior to powering the duino, i.e. http://www.arduino.cc/cgi-bin/yabb2/...num=1191452682 , the claim is that bits were randomly inverting without it?

And they have a document describing vehicle interfacing, with both an opto-isolator and a transistor based (similiar to the supermid).
http://www.arduino.cc/playground/upl..._4_arduino.pdf


But FYI, there are a number of already built models with the zeners (since the beginning of may), and I need to know for certain that we have a problem and exactly what the problem is before I ask folks to disassemble their boards and add stuff to them. It also tends to result in more complicated than necessary circuits if each addition goes unchallenged. The zeners may very well be inadequate protection, but I need to see it before complicating the assembly and price and affecting the installed base. It may be that we add opto-isolators and a 12v regulator ahead of the arduino before we call it version 1.0, hopefully the o-scope will make that decision a no-brainer.

re: production, I'm not really in this project for the money, really it is just to learn (plenty of that going on) and have some fun It's just a hobby at this point, though I'd be a fool to turn down some small kickbacks on a reasonably priced kit or pre-assembled unit. But not even thinking about manufacturing these at the present, as that would take a lot of the fun out of it. I *might* have it together enough to put a PCB and small pile of parts in a baggie, but it isn't really my thing.

I think about the work other folks are doing though, a lot. The project doesn't exactly have enough funds to call it a budget at the present. But I do keep the other contributors in mind, folks willing to buy some hardware and see if it works, and run tests, and do research, and keep the project towards the goal. I would like some ideas about how to identify and compensate, if even in token only, the folks that are helping to make this happen.

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Last edited by dcb; 06-14-2008 at 04:43 PM..
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