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kevin gilmore

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Everything posted by kevin gilmore

  1. kevin gilmore
    the HV boards, the 3n254 is .15 spacing, and the board is .15 spacing any of the tiny 1 amp ones will work. on the LV board the spacing is .20, and its definitely a different bridge, the same one used in the ksa5 power supplies rated for 10A I think
  2. kevin gilmore
    this is a reasonably cheap version, probably a very good idea if you are doing T2's http://www.micromark.com/microlux-tapping-fixture,8363.html
  3. kevin gilmore
    the name of the game is to keep the tap completely perpendicular to the surface i got a super old tapping jig that does just that, so simple to use, and the 10 inch or so handle makes it easy to figure out how much torque to apply
  4. kevin gilmore
    i hate microsoft remotely administered computer requires an ok to change the kernel... (brilliant) fixed now. does not seem to happen very often
  5. kevin gilmore
    the angle brackets bolt to much bigger heatsinks, same way as T2 because the sicfets are bigger I am now using 1.5 x 1.0 inch aluminum angle bracket .125 thick
  6. kevin gilmore
    2 X 22 volts should be just fine, still need some heatsink on the pass transistors does not seem to be a standard value though
  7. kevin gilmore
    separate bias wires for each side, plus an antenna to detect arcing same as quad esl63's amplifier has much more voltage swing than hev90
  8. kevin gilmore
    1) 35V 581-TAP476M020CCS don't have a link for the 10uf 2) does not matter I used these 810-FK28C0G1H470J 3) I used these 505-MKS2-4.7/50/10 which are in stock and 50V, more than enough 4) I used these 505-MKS2.01/63/10
  9. kevin gilmore
    yes absolutely. If the outputs to the minus rail short out, then you are putting close to 900v on the diaphrams. Same as any other direct coupled electrostatic really we should have a protector for this. The 5.1k resistor is to prevent death to humans in case something bad happens. and as for the new sennheisier product, boy are some people over there delusional thinking its going to be only $15k.
  10. kevin gilmore
    10 ma for the driver is more than enough. needs to be 3 transformers, 2 of which have 4 windings of 380vac each the other is the kgsshv-carbon transformer
  11. kevin gilmore
    yep that is the idea over the weekend i replaced the 1.5k resistors with 2k original vishay resistors rated at .01% and 5 ppm voltages much more accurate. version 5 of the goldenreference board has a place for 1M pots that go in parallel with these resistors for those that just absolutely need to adjust to 6 places (actually those pots may influence overall thermal stability, cermet pots required)
  12. kevin gilmore
    1.25 volts 160 ma current draw on each rail at 20v
  13. kevin gilmore
    the circlotron is the only push pull fully direct coupled electrostatic amplifier that is buildable with current parts. Also at 25ma, rise and fall time are faster than any other electrostatic amplifier of any kind.
  14. kevin gilmore
    balanced in, balanced out, 7vrms out into 50 ohms 1khz goldenreference power supply at +20.0000, -20.0000 (hand trimmed resistors) thd is .011% which is actually the base line of this particular meter typically .003% on the quantasylum400 and less on the audio precision
  15. kevin gilmore
    a complete set of boards is 2 x output boards 2 x driver boards 4 x single hv900 power supply boards (or 2 duals which won't fit in a single box) 1 pair of fat power 450v supply boards (or the dual which also won't fit in the box)
  16. kevin gilmore
    the display is part number dd-52 and in the usa you can order at 800 833 9200
  17. kevin gilmore
    I just updated to what I think is the final board, I added a ground layer on the inside and flipped the relays on the top for uniform ground plane.
  18. kevin gilmore
    birgir got one from likely the same source, I bought one from a usa source. for sure they are all going to need new VF displays which are about $100 with shipping from Tektronix. The replacement of the display is not easy, many very fine traces, need the proper unsolder gun. that said, these are great for doing electrostatic measurements as they go higher in voltage than any other thing out there but have a low end limit of about .02%
  19. kevin gilmore
    #4 it is, new file posted v42 which is actually 4.2 but I'm lazy
  20. kevin gilmore
    the production board will be 2.0 inches wide, reduced from 2.05 inches wide so that the input/output jacks line up perfectly. i can also change the hole size to #4 if people want.
  21. kevin gilmore
    the holes are .125 inch, good for a #6 screw. I can certainly make the holes smaller for production boards. the 50 ohm resistors are the bigger ones, those attenuator resistors are the smaller ones. remember that the board is 2 x 3 inches, on my screen it shows up at about 2x other than the 3 caps, there are exactly the same number of components on the back of the board
  22. kevin gilmore
    typical high voltage zeners are +/-3% no matter what the specs are the el-cheapo meter works great for hand picking parts
  23. kevin gilmore
    posted for congo5 power supply board known working as expected from kerry's and my prototypes for the 400v version, input AC needs to be at least 310vac which would make 350vac necessary for the 450v version so with clearance i would pick 360 vac under load for the 400v version (500v caps sufficient) and 390 vac under load for the 450v version (550v or more caps sufficient)
  24. kevin gilmore
    hard to see if its really copper from that angle, but what probably happened is that the photo mask lifted at the edge and caused that.
  25. kevin gilmore
    on the old boards, you need 2 boards for balanced. the new board is balanced all on one board.
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