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  1. duke37

    Da sander blowing fuses ?

    Use a vernier gauge or a micrometer. If you do not have either, wind ten turns close wound on a rod, measure the length of the coil and divide by ten. Remember that the overall wire diameter will be larger than the copper due to the insulation. Too thin a wire will get hot if you drive hard...
  2. duke37

    Da sander blowing fuses ?

    I suggested that you checked the resistance between the wires. They depend on the enamel insulation and if this has failed you should see a burn. The core has a mark on it where the wire migh have arced. This has not caused the short, it is the other way round. You could fill the depression...
  3. duke37

    HM 10 range problem..?

    Does Does that mean the wavelength is about 125mm? If so a set of 60mm rods set in a parabola with the Tx/Rx at the focus should increase the signal in one direction.
  4. duke37

    Ring Doorbell

    I do not understand why a wire wound resistor is mandatory. Resistors contained in an extruded aluminium tube which can be bolted to a heat sink are available.
  5. duke37

    HM 10 range problem..?

    Depends on the frequency but a parabola behind the device with the device 'looking' into the parabola will help. I have had a transmitter on 27MHz using a 2N706 at about 10mA being picked up at several miles, just a quarter wave vertical each end.
  6. duke37

    Da sander blowing fuses ?

    The toroid looks like an inductance to reduce interference being sent into the mains. It will have two wires bifilar wound and each wire should have a connection input to output and no connection between the wires. If it smells or looks burnt then the wire insulation has failed. It is possible...
  7. duke37

    Da sander blowing fuses ?

    The power goes through the toroid to the motor and it needs to be conductive, it should have one wire for the line and another for the neutral. Breakdown of insulation between the wires will blow the fuse but so will faulty motor coils or armature. Carbon dust from the brushes may also be a...
  8. duke37

    Which relay should I use?

    Paralleling relays will not increase the voltage capability, just the current that can be handled but you may have trouble if one relay opens a fraction of a second before the other. The second relay to open will have to break the total current. If there are duplicate pins, then use both to get...
  9. duke37

    Which relay should I use?

    You are getting mixed up between the energising voltage and the maximum permitted switched voltage/current. The relay needs 48V +/- to switch. Connecting two in parallel still means 48V. Connecting two in series will need 96V so your 88V may not be enough particularly when the supply is under...
  10. duke37

    Connecting wires

    If the wires carry more than 1A at 12V then get a qualified electrician with insurance to do the job. You should not learn how to do things when others are at risk.
  11. duke37

    Which relay should I use?

    I have been trying to follow this thread without success. It seems that there is a mix up between the relay coil supply and its switching capability. To switch motors between wye to delta, contactors rather than relays are used since they are made to stand the energy generated when the contacts...
  12. duke37

    Connecting wires

    I would use heat shrink sleeving for insulation but it is too late if the wires are already joined. I would also solder for a good connection.
  13. duke37

    Which relay should I use?

    Three times 24V = 72V, connected in series, probably near enough to stop the relays overheating. Wire them up so that they are not energised for most of the time..
  14. duke37

    power electronics questions

    Yes, we can help but it is help only for homework. To start, what are your answers to the questions. Show your calculations and we will advise if you get them wrong or get stuck.
  15. duke37

    180vdc to 75 vdc

    "can i get any cicuitry.." Search for 'computer power supply schematic'
  16. duke37

    9500v to 9.5v

    My brother has an electric fence and he lets some grass grow up to the wire. He then can hear the ticking on his telephone.:) I would not put a low voltage device near an electric fence. To get a reduced voltage, I would use a capacitance, perhaps a few cm of parallel wires. You could also use a...
  17. duke37

    Parallel and series generator and batteries

    You are getting confused between A and Ah. 12V and 12A = 144W 24V and 12A = 288W Where does the extra power come from? You need an extra two generators as Steve says.
  18. duke37

    Parallel and series generator and batteries

    It would not work, why are you fixated at running the generators in parallel which can only charge one battery?
  19. duke37

    180vdc to 75 vdc

    A computer power supply rectifies the mains to give a very high DC voltage which is then chopped and fed to an inductor/transformer to get lower voltage and this is then rectified to give DC output at various voltages. It would be feasible to rewind the inductor to give the voltages that you...
  20. duke37

    Parallel and series generator and batteries

    This is what Steve suggested many posts ago. The batteries are in series also the generators. Each generator charges its own battery.
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