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  1. hevans1944

    Name that switch!

    As you can see, from reading the OP's comment in post #19, he has already tried this approach and found it lacking. EMG is much more difficult instrumentation than EEG.
  2. hevans1944

    Conditioning Electronics

    The non-inverting (+) pins on both op-amps are grounded (at least according to the schematic) which means the inverting pins (-) are maintained at a "virtual ground" by feedback from the op-amp outputs.
  3. hevans1944

    Conditioning Electronics

    Yes, it is. Thanks for noticing that. I edited my post #3 to correct it. No, it puts -15 volts on the input resistor, R, of the last op-amp. After the offset necessary to make the output zero at 50 psi (-5 V) is removed by Vref, there is effectively -10 V on the input of the second op-amp and a...
  4. hevans1944

    Knowledge and book sources needed to finish an embedded system design project

    You need to learn about video frame-grabbers and video image processing on a frame-to-frame basis. Basically, for each frame of video captured, you will identify pixels, or contiguous groups of pixels, that match the identification "dots" attached to the moving subject. The x-y locations of each...
  5. hevans1944

    Conditioning Electronics

    The input voltage, Vo, varies from 50 x 100 mV/psi = 5 V at 50 psi to 150 x 100 mV/psi = 15 V at 150 PSI. Since you want the output, Vout, to vary from 0 to 2.5 V, the range of the input signal, which is 10 V (V150 psi - V50psi), must be attenuated by a factor of 2.5/10 = 0.25 and then the input...
  6. hevans1944

    8-Pin Development Board

    The 14-bit CONFIGURATION word at location 0x2007, described on page on 54 does not enable or disable the analog-to-digital converter or the analog comparator. Nor can you read or write to it with instructions in your program: it's address is out of the range that program memory can address...
  7. hevans1944

    Name that switch!

    Maybe not. They are doing a lot of wonderful things with ultra-low power electronics today. Nano-watt and pico-watt type stuff.
  8. hevans1944

    Oscillator and transformer project

    Sounds like a plan! Post here again if you need more ideas.
  9. hevans1944

    Name that switch!

    Hadn't thought of using a washing machine fill-switch as a sensor. Should work, but as you said, tricky to set up. A linear pressure sensor would be better. Sorry about the "energy harvesting" statement. I just assumed, since you were charging a capacitor with the piezoelectric microphone, that...
  10. hevans1944

    Name that switch!

    I like the thought of energy-harvesting a piezoelectric microphone as a motion sensor, but the output would be minucule IMHO. The silicone rubber hose, used as a sort of bridle with pressure sensor attached, seems most practical. Perhaps a cheap piezoelectric microphone (or crystal ear-bud if...
  11. hevans1944

    Electric skateboard battery

    You can connect batteries in series for more voltage and re-charge each one separately to maintain charge balance. But do the math on how long they will last before needing to be re-charged. @BobK is right: hydrocarbons (food) work best to power a skate board. I still like steam engines though.
  12. hevans1944

    Will this switching down-regulator protect at all against short-circuits?

    Quadcopters don't need a battery to blow up. They crash easily enough from other causes, but a fast-blow fuse in the battery supply wires is a good idea.
  13. hevans1944

    Trouble with solder

    And perhaps you should buy a few spare motors too, for use after you melt the plastic-insulated parts of the motor if you don't like the idea of using a band-clamp instead. If you have access to an AC heli-arc TiG welder, and a friend who knows how to use one, it takes only a few seconds to weld...
  14. hevans1944

    Jacob's Ladder help

    Well of course it will "work," as the video demonstrated. It just doesn't work very well. Is it "safe"? I would keep my eye and nose tuned for smoke from the transformer. In the video, there does not appear to be enough voltage in the "open circuit" state to strike the arc. An ordinary...
  15. hevans1944

    Name that switch!

    That's sad. And the main reason I don't believe in patents as the law is now written. The little guy doesn't stand a chance. And if you DO manage to get a patent, you reveal your "secret" for everyone to see and the crooks will copy it. My preferred method of IP protection is the "trade secret"...
  16. hevans1944

    8-Pin Development Board

    The configuration word defaults to all bits set unless you change it at the beginning of your program (before any code) using the __CONFIG directive. As you can see, this is mainly used to enable and disable certain "features". I would recommend that bit 3 WDTE: Watchdog Timer Enable bit be...
  17. hevans1944

    IGBT Half-bridge Module Help

    It looks like Vishay brought the gate-control return lines out to separate pins, so you don't get switching currents from the load in the return lines when you drive the gates. So you use pin 10 as the gate drive return lead for the gate driven on pin 9, and pin 12 as the gate drive return lead...
  18. hevans1944

    Will this switching down-regulator protect at all against short-circuits?

    None of these things will happen IF the LED has an appropriately sized resistor in series with it to limit the current.
  19. hevans1944

    Electric skateboard battery

    @Gryd3 and @Martaine2005 : You are both right on, and clearly on the same page. Hydrocarbons is the way to go with a skateboard! Or anything that efficiently moves people and cargo from here to there. I would work on constructing a coal-fired steam engine for that skate board. Steam-punk seems...
  20. hevans1944

    Will this switching down-regulator protect at all against short-circuits?

    There is this note from the device datasheet: Overcurrent/overtemperature behavior If the current limit has been considerably exceeded or if the device is overheated the product will gradually reduce the output voltage in an attempt to reduce the load on the device. Once the extra load is...
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