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  1. sbkenn

    Alternator design

    Understood. Thanks.
  2. sbkenn

    Alternator design

    Hi all. Is there a correlation between turns and output voltage at a particular frequency in alternators, or does it also depend on flux density through the coils ? TIA.
  3. sbkenn

    Scania obscure detains

    Hi All. I have a relatively modern DSC9 where I have removed the electronic controls and attached a lever and pushrod to operate the power control. Does anyone know: 1) If there is a TDC sensor ? 2) Does the #1 injector piezo sensor fire on needle lift and/or needle drop ? 3) What injector...
  4. sbkenn

    Ball-valve insert

    A fair comment .....
  5. sbkenn

    Ball-valve insert

    Hi. Does anyone know if there are available ball-valve inserts which can be dropped into a recess in a manifold. If so, what might they be called or where I might find them. I want some, probably 1 1/2" or 2" for a fuel fill and tank to tank transfer in a small ship. TIA
  6. sbkenn

    Prestressed reinforced concrete beam

    [thumbsup]
  7. sbkenn

    Prestressed reinforced concrete beam

    Thanks for that. Weight really isn't an issue. The vessel (ex-Minesweeper) was designed to be 116tons dry, 164 fully loaded. She is currently about 100tons. The British Navy removed about 15 tons of equipment when converted for training. I removed about another 4, then added about 5 in...
  8. sbkenn

    Prestressed reinforced concrete beam

    Hi all. I am considering getting a prestressed reinforced concrete beam fabricated to stiffen the keel of a 100ft wooden boat. The proposal is a 16" x 8" or maybe 12 x 6 box section with 4 reinforcing rods, then filled with concrete. The concrete & rods would provide most of the stiffness...
  9. sbkenn

    Pure sine wave inverter

    Are pure-sine-wave inverters ALWAYS less efficient ? I am particularly interested in low or zero load efficiency. I suspect that, living off-grid, that I need a low-power PSW one for loads that need it or require it to be on all the time, and a heavier, NSW(non sine wave) one for occasional...
  10. sbkenn

    Stepper controller

    I think I will just microstep a geared motor for more than 60degree gauge. Less than 60 degrees just use a fixed voltage on one coil, then analog voltage on the other.
  11. sbkenn

    Stepper controller

    Does anyone know of a device to interface analog temperature/pressure or other sensor, directly to a 2-phase stepper-type analog gauge ? TIA
  12. sbkenn

    Wing in Ground effect

    I am considering using just the fuselage, strakes and main spar, as I have them already built. Sea Sled hull, and possibly adding a high tailplane on twin-booms. Canard would be ineffective in GE. It would be a bit more interesting than just putting an outboard motor on it ! I have asked on...
  13. sbkenn

    Wing in Ground effect

    Hi. Are there any tables or rules-of-thumb on the power reduction needed to fly in ground effect compared to above it ? I built a Cozy, a derivative of the Rutan Long-Eze, but due to deteriorating health, I won't be allowed to fly it. I am considering adapting it to fly off water, in...
  14. sbkenn

    DC electric motor

    Hi. Can someone confirm that adjacent commutator segments SHOULDN'T read zero ohms ? I just received a replacement armature for a small starter motor, and almost immediately noticed that the cuts to separate the segments don't look like they go all the way through the copper. I don't have a...
  15. sbkenn

    "Ideal" diodes

    The other variety, ones which DO have a Gnd connection, work with a small forward voltage, the ones that I looked at has 30mV. What there response time is, I haven't determined. I presume there is a switched-capacitor converter to generate a decent Vgs.
  16. sbkenn

    "Ideal" diodes

    10k RPM -> 160Hz x 6 pole-pairs -> 1kHz. Not HF in electronics terms.
  17. sbkenn

    "Ideal" diodes

    I suspect that the ones I have are intended, and only suitable for, DC blocking diodes. The Bosch/Infineon ones are for car alternators and chargers i.e. low frequency rectifiers, and I haven't found any way of procuring a small quantity. I think they are only going to manufacturers in that...
  18. sbkenn

    "Ideal" diodes

    IRstuff : exactly. Some controllers use 0v and supply V, and used a switched-capacitor circuit to derive the greater-than-Vin gate voltage. The ones that I have don't have a 0/negative connection, so have to switch off the FET in order to derive power from the 0.7V drop across the body diode...
  19. sbkenn

    "Ideal" diodes

    An incandescent light-bulb is pretty close if you need heat and light !
  20. sbkenn

    DC-to-DC Converter Modelling

    First determine how much power you want to transfer, isolated or not, then input and output current/voltage ripple is acceptable. That will determine switching frequency and thereafter the topology, core and capacitor sizes.

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