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Recent content by potteryshard

  1. potteryshard

    DOT lighting regs?

    Who can even see the taillights? As a driver of a small car, I'm constantly blinded by the headlights of the pickups (habitually five feet) behind me. Because trucks are allowed to place headlights higher than the side-mirror locations of cars, the mirrors are on-axis to the low beams of the...
  2. potteryshard

    LED lights

    If I recall correctly, there is also a substantial performance difference between the foveal part of the retina, which is conprised of mostly cone cells and the periphial areas comprised mostly of rods. Not only are the rods more light sensitive, they are also faster. This makes sense from an...
  3. potteryshard

    Video: Diesel engine knocking noise

    Broken valve spring? No seal during cranking, but valve would slam shut during compression stroke.
  4. potteryshard

    Help with Hydraulic Catwalk

    The video seems to show two different motions; first the whole track assembly tongues out one ram's worth. When that cycle ends, the chain drive seems to start.
  5. potteryshard

    Help with Hydraulic Catwalk

    Hydraulic motor on carriage with attached pinion which engages rack welded to structure? Rack can easily be assembled from short pieces of prefabricated rack section. Hoses to motor carried on festoon trolleys.
  6. potteryshard

    Tricky wind turbine question

    I've thought of using a water brake. Essentially a low-efficiency hydraulic pump mounted on the main rotor shaft with no fluid outlet. The only outlet for the pressurized fluid is the pump clearances. Under normal running circumstances the water brake is dry; no seals, no losses. If the...
  7. potteryshard

    Brushless DC motor as AC Generator (Automotive Application)

    This looks like a good product: http://www.gener-nator.com/orders.htm
  8. potteryshard

    Brushless DC motor as AC Generator (Automotive Application)

    There are a variety of alternators constructed to resemble generators for the vintage car markets. I don't have any references at hand, but have stumbled across ads for such replacements on many occasions.
  9. potteryshard

    What load must be available for motor while starting in Y/D?

    On a hydraulic crane I'd expect the motor to start unloaded, and to run continuously.
  10. potteryshard

    DC Motor - Please Help

    Given that it ran smoothly at 12 V, that the coil resistances are extremely low, and that no nameplate exists, are you certain it is a 90 V motor?
  11. potteryshard

    limit rotational speed with a mechanism?

    The fan or friction controllers are simple and do work, but waste most of the spring energy. The escapement mechanism of a mechanical watch is highly efficient, but as usually configured results in a very low speed intermittent action. The concept could be adapted by arranging that the...
  12. potteryshard

    Is harmonics blowing up my capacitors??

    You may want to check fundamentals first... Are the capacitors rated for the applied line voltage? Connected delta with a wye voltage rating?
  13. potteryshard

    Kids building things.

    Civilized life (and the requisite inventiveness necessary to support same) is not possible without a welder at hand. I completely fail to understand how some people can live without a small MIG and a portable band saw at hand... Positively stone-age! I'd suggest that some basic metal-working...
  14. potteryshard

    20W LED tube interchangeable with 20W fluorescent tube.

    As I recall, flourescent ballasts also include an autotransformer (or electronic conversion) to change line voltage to a voltage suitable for a particular lamp design. Voltage may be near line voltage, but likewise may not. Also; flourescents, especially the high-output versions, want to be...
  15. potteryshard

    AC over DC

    DC transmission lines can carry more power on a given conductor not because of current-related losses, but instead because of voltage. The peak voltage of an AC line is 1.414 times the nominal voltage. The peak voltage of a DC line is the nominal voltage. The voltage that a line can be...
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