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Everything posted by jstevenperry

  1. I figured the 6-8V running into the 7805 in the picture should be more towards 8V than 6V :->. I've not worked with the LM2931. The most common type of +5VDC regulator I've seen is the 7805 (276-1770 from Radio Shack). But, like you said, the 7805 won't work with less than 7VDC input. The assumption I was working off of for my comments was based on gogo2520's comment about using a 9V battery as the power source. --steve
  2. Nicely stated. My point exactly. It is a "difference." Which means its nature is inherently linear (and thus requires two points in space).
  3. This looks interesting. Another "code without code" type of development system, right? I wonder how well it works...
  4. I'm with gogo2520 on this one. You should only need one battery to power the 7805 regulator, which will provide a steady 5V to your PIC. The output i/o pins on the PIC will provide the necessary voltage to drive the LEDs, right? Just make sure to put an appropriately sized resistor in series with each LED to make sure not to overdrive them (based on whatever the current coming out of the pIC is).
  5. I've heard that it takes a fair bit of pressure to activate the mechanism, which makes it difficult to use for some delicate operations.
  6. You pose an interesting question. Is there a potential difference even if I don't measure it (by connecting a Voltmeter to two points in the circuit and measuring the difference between the two points)? I guess the answer, from a quantum mechanics standpoint would be, well, maybe. But, unless we take a measurement (and thus interfere - albeit slightly due to the Voltmeter's incredibly high input impedence - with the system) we don't know what the potential difference would be. Still, since voltgage is always measured as a difference in potential between two points in space, what is the phys
  7. I don't know where the original came from, but I just selected the "
  8. I think some people just like to start arguments... not a single reply from this guy to the responses to his allegations that this site is useless...
  9. Voltage is not the number of electrons in a block of conductive material (nor the energy contained within them). It is a *potential* (as you mentioned) for those electrons to flow, which, by definition, means it MUST BE measured relative to some other point. Unless compared to some other, different, potential, the number of electrons in a block of conductive material cannot be said to have a *voltage* as they are all electrically common. Your voltmeter with one lead will never measure a meaningful voltage. Your voltmeter with one probe makes for interesting philosophy (like the Zen koan of "o
  10. Oh great, audioguru, please lend us your wisdom and expand on your comments. An op am relies on differential voltage (so that it may amplify accordingly), but please explain how to supply a "negative" voltage to any given circuit (and what that means). This concept has eluded me as well. Thanks.
  11. I've noticed that too. But not only that, it seems that the more rural areas have the least up-to-date satellite photos based on recent expansion in Little Rock that is not reflected in the photos, and comparing that to more urban areas like, say, the Atlanta metro area. And areas of forrest will be different colors, I guess indicating that they were taken at different seasons of the year.
  12. That's neat. And so is google Earth. I must have spent 4 hours the first night I installed it looking up the addresses of different people I know.
  13. I requested and got the Digikey catalog one time in the mail. It was a little overwhelming. Thanks for the links. btw - AR is Arkansas, Arizona is AZ. It's a common mistake.
  14. I appreciate the reply. I have only built one of the projects (Issue #2 - Mousebot), but had to get the parts from two different places because of price. I got the motors from Solarbotics, and everything else from Jameco. (Jameco didn't have motors small enough to fit in the mouse case.) So I paid like 2.35 each for motors and 7 bucks or so for shipping. To make it worth it I ordered 10 motors. I live in Little Rock, AR, USA, so if a part I need isn't at Radio Shack (and sadly, that is becoming more and more the case) I have to order it. I'm finding there are SO many electronics stores online
  15. I'm a fan of the Radio Shack 29 Function DMM. It does everything I need. But if you want a cheap Capacitance meter, Radio Shack has a 49 function DMM that supposedly checks capacitance within a certain range. But if you want to go that far, get yourself a good LCR meter.
  16. If you have an idea, I'd like to hear about it. I have a few of my own. Maybe we could collaborate?
  17. I did a search for this, so if it's redundant, I apologize in advance. I'm not affiliated with the magazine, other than I am an author of books from the same publisher (O'Reilly). This magazine is great. But I've wondered if anyone else has had problems with parts availability. That's my main question. Seems like the projects in the mag require parts that can only be acquired from different dealers. Is there a market for the projects from the magazine? I could definitely order the parts, put them all together and tell you guys where to get them. Or --- let you guys order them from me. Cut out
  18. I agree with all of the postings I've seen, and it's funny that I too am here because of a google search. Seems like I've found a home. I want to underscore the point that before asking for help that you try and get that help on your own. google.com is a great source. But sometimes it's not enough. So, I'm here, and I hope I won't be too much of an annoyance to anyone. But I think from the posts I've read that you guys are the experts (and are always happy to help us newbies that try to find answers, but run out of options for whatever reason), so when google.com can't help me, I'll come here
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