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  1. BobK

    Testing Digital Display

    As far as I can tell, this module is a voltmeter with an analog input. There is no way to control the segments except by putting an analog voltage on the input. You could make all the segments except the decimal points light up by putting -1.888 Volts on the input. Bob
  2. BobK

    PIC16F84 Assembler - Absolute Mode Issues

    An interrupt causes the program to start execution at address 4. You must have an interrupt handler starting at that address. You have enabled interrupts with no interrupt handler, which causes the PIC to jump to address 4 in your program. Try this: ORG 0 goto start ORG...
  3. BobK

    Home Made Osciloscope

    Just curious, does the PICAXE support in circuit debugging on the as well? Bob
  4. BobK

    diode for collapsing magnetic field

    I get what you are trying to say, but it is not correct. The current decreases due to losses in the coil resisntace and the diode until it is zero. Bob
  5. BobK

    Simple Relay

    The other option, which might be better, is to use a SPDT relay and connect the NO contact to +5V and the NC contact to ground. Bob
  6. BobK

    ? on Resistor placement w/ LEDs

    I prefer to get my buzz a kinder and gentler way. Bob
  7. BobK

    A kinetic phone charger project

    No, Lithium Ion batteries are charged first with constant current until it drops off then a constant voltage of about 4.2V. It is not a simple circuit. However... You generator is not likely to produce the current needed to charge in constant current mode, but it probably could be used to...
  8. BobK

    diode for collapsing magnetic field

    The diode across the pump needs a 30A rating at least (same as the pump) Bob
  9. BobK

    A kinetic phone charger project

    By the way, I am probably being a little too subtle, but I don't think your project is realistic. However, I would encourage you to experiment with it and see what you learn. Bob
  10. BobK

    A kinetic phone charger project

    Yes, you would need a charging circuit. I doubt that 2 Amps or 1000V would be exceeded. If you have a multimeter, try putting a smoothing capacitor after the bridge and measure the voltage you get. Bob
  11. BobK

    Simple Relay

    Depends somewhat on what is driving the 5V. I would start with 1K near the input to the computer. If the 5V is capabable of driving more current, you could reduce it if necessary, to say 100 Ohm. So where is the 5V coming from? is it directly connected to a power source, or is it the...
  12. BobK

    A kinetic phone charger project

    Look at this: http://en.wikipedia.org/wiki/Diode_bridge Connect the AC input to the coil and the + and - are the DC output. Bob
  13. BobK

    Simple Relay

    When the relay is open the input line is floating? If so, a resitor to ground should help. Bob
  14. BobK

    A kinetic phone charger project

    A magnet going back and forth thorugh a coil will produce AC. You would need to rectify it. I also hope your customers are ready to shake vigorously for a couple of hours to charge their cell phones! Bob
  15. BobK

    10 Ohm 100W Tapped Resistor

    We should buy these up and send them to all the people who want to slow down 20A motors with a resistor. bob
  16. BobK

    series battery

    I don't think you get that result unless two voltmeters have the same impedance, do you? bob
  17. BobK

    constant output why for buck converter????

    If the input and the load are constant, you can run a buck converter without feedback. Be aware though, that the formula: Vout = Vin * D Works only when the converter is running in continuous mode, i.e. the current in the inductor never saturates or falls to zero, it must look like a...
  18. BobK

    H-bridge with 4 N-ch FETs

    A full bridge driver usually means an IC that drives the motor directly. What you need is a MOSFET gate driver with high-side and low-side drivers. I think most of these come with one of each per package. I don't seem to be able to find any that have 2 of each in a package, so you will need 2...
  19. BobK

    constant output why for buck converter????

    Well, for starters you are using an N-channel MOSFET where a P-channel is needed. bob
  20. BobK

    series battery

    Let's say you have two guys who can each throw a ball 30 feet high. You position the first guy on the ground, and the second on a 30 ft high platform. The first guy throws the ball to the second guy. Then the second guy throws the ball 30 feet up. How high did the ball go? Bob
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