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  1. BobK

    Designing

    Ones that interest you. Bob
  2. BobK

    [woo] Does anyone know of this breakthrough technology ?

    From your link: The "Force" is a unique non-grounded component. A “Force” unit (box) is connected in parallel (one “Force” unit to each phase in your electrical panel with a single wire), is not grounded, and therefore it cannot pose any threat to your system as a complex grounded device...
  3. BobK

    distance measurement

    From the 3D Robotics site: Bob
  4. BobK

    Question about how resistors work

    The three elements (two resistors and meter) are connected in series. Components in series always have the same current flowing through them. Bob
  5. BobK

    tablets for kids

    Did you try calling the telephone number the have on the home page? Bob
  6. BobK

    [woo] Does anyone know of this breakthrough technology ?

    Can we get a woo woo label for this one? Bob
  7. BobK

    Charger circuit help!

    Are you sure of the transistor type and pinout? Bob
  8. BobK

    Charger circuit help!

    I don't think the circuit is correct. Please recheck it. Problems: I think the center tap must be to the ground, and each other end of the transformer secondary must go to a diode. The way that transistor is wired, it could never turn on since the base voltage is < the emitter. Bob
  9. BobK

    Bluetooth and Radio Frequency?

    I think this is the best idea yet. Bob
  10. BobK

    TRANSISTOR SELECTION

    Which has no effect since the power supply is already shorted by the second vertical wire from the left. Bob
  11. BobK

    Bluetooth and Radio Frequency?

    Even if you get phone - Bluetooth - Arduino working, you will either need an external DAC or be satisfied with fairly low quality sound. Bob
  12. BobK

    Joule Thief Is Not Working

    Funny then that it needs such a low resistor, since mine works okay with 10K. It must be the transistor. Can you try a new 2N3904 or PN2222? Bob
  13. BobK

    Storing energy in Capacitors

    The energy density of even super-capacitors is much less than that of batteries. I.e. for the same weight / volume, a battery will run your LEDs many times longer than a capacitor. Forget the capacitors, what you need is a rechargeable battery. Bob
  14. BobK

    Joule Thief Is Not Working

    How many turns did you end up with? And how did you wind it? The one I wound has 22 turns with the wire doubled, then the loop cut to make two windings that are perfectly interspersed. I am using a 2N3904. Bob
  15. BobK

    Understanding PWM with PIC (assembly)

    Great! Glad to be of help. Bob
  16. BobK

    Bluetooth and Radio Frequency?

    You can by FM transmitters that plug into the headphone jack and do exactly what you want. No need for Bluetooth. Bob
  17. BobK

    Multiple Inputs/Outputs transmitter

    You can buy these transmitters and receivers with the encoder. http://www.ebay.com/itm/433Mhz-RF-Link-Kits-With-Encoder-and-Decoder-/280526085609?pt=LH_DefaultDomain_0&hash=item4150a85de9 Bob
  18. BobK

    Joule Thief Is Not Working

    Mine works with a 1K and a little less bright with a 10K, so the resistor is not very critical. Bob
  19. BobK

    how to distribute voltage locally on a surface?

    100 x 100 is nothing. The display you are looking at right now probably has on the order of 1000 wires coming out on each of two perpendicular sides. Bob
  20. BobK

    1650w electric conversion

    Actually, no, they require no transformer. The power coming in on the poles is (usually) 3 phase. the transformers go across any 2 of them, and are balanced across all the houses. Bob
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