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kevin gilmore

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Everything posted by kevin gilmore

  1. kevin gilmore
    unscrew the red barrel on the hv probe and notice the accuracy of the resistor.
  2. kevin gilmore
    this is all about the real impedance of the dmm. Almost all of which are specified as 10M. But when you actually measure them, all over the place. especially if you have over-voltaged the thing a few times. So its a random number generator. The real ultra high impedance meters are expensive, and the high voltage probes are +/-10% it would be nice to get rid of all the zeners in the bias supply with some ultra accurately regulated power supply. it would be much lower noise, but way more complicated. pretty much another hv supply with smaller caps
  3. kevin gilmore
    The test point on the power supply is low impedance! So 580 there is 580 no matter what kind of meter you use. most of the other amps don't have test points, and the only thing you can do is measure at the stax jack which is 4.7M away from a low impedance voltage source. for all of my newer power supplies, the 580v is generated with zener diodes, and is not adjustable like the much older supplies.
  4. kevin gilmore
    absolutely true for safety reasons. AND FOR NO OTHER REASON! but for minimum hum, everything inside the chassis including power supply ground, rca ground, and any ground referenced outputs should float from the chassis. works way better that way.
  5. kevin gilmore
    nope, a standard 10meg input impedance dmm is going to read about 30% to low. the high voltage probes have a 1Gohm impedance, so far more accurate.
  6. kevin gilmore
    fixed the 4.7k resistor and the size of the 5pf caps the accuracy of the resistor is not critical, I picked the standard value.
  7. kevin gilmore
    all board files should be fixed, please check
  8. kevin gilmore
    feel free to stuff whatever you want into whichever hole you desire (paging steve) will have to order a couple of parts from Canada to make sure, unless someone knows of a usa distributor.
  9. kevin gilmore
    while that would work for the unregulated input, for the output, its a bunch more work so I will do the layout with O+,I+ shorted and O-I- shorted all files updated, please check that I hooked everything up to the right place.
  10. kevin gilmore
    if you wire the 4 wire caps the way they want you to wire, the board would have to change a fair bit to use those caps, then you could only use those caps. (board sizes would stay exactly the same) 5 more board types... I can do that... not sure how they would like getting I+ wired to O+ and I- wired to O- if anyone has experience with these caps...
  11. kevin gilmore
    is there any interest in the mundorf 4 wire capacitors? I could change the 4 pin kemet to the 4 pin mundorf, or add the mundorf in addition which might get a bit messy
  12. kevin gilmore
    there have been updates in the boards to replace the 1 x 300k or 510k resistor with 2 x cmf60 resistors. although there is conflicting information from Vishay with 2 documents saying different specs for the cmf60. I think that in any case, the 2 x cmf60 has to work because the total power is 1 watt and the total maximum voltage is 550v someone have a different idea, I can certainly do that. the pdf I am going by is this http://www.mouser.com/ds/2/427/cmfind-239942.pdf the conflicting document is this http://www.vishay.com/docs/31027/CMFMIL.pdf
  13. kevin gilmore
    pcbnet actually has the large board runs made in china. only the rapid response stuff is made in Illinois quality is very good however, the T2 boards were made by them (my production)
  14. kevin gilmore
    the 1k resistor in series with the 2 x 11k resistors. change to 500 ohms and I never liked virtual ground anything. just a bad idea.
  15. kevin gilmore
    the problem with the e12 is the common summing. so even if you do 2 boards, and one hot output is +2v and the other hot output is -2v, the result is zero. if you think that can't happen with some of these whacky dacs, think again you really do need a pair of comparators on each of the 4 lines
  16. kevin gilmore
    you can change one resistor and the setpoint will be .25v or anything else you want. the e12 does not protect against dc offsets at the imput causing differential output voltage that can be significant but adds up to zero and then won't trip the relay
  17. kevin gilmore
    updated picture
  18. kevin gilmore
    http://www.mouser.com/ProductDetail/Phoenix-Contact/1902547/?qs=sGAEpiMZZMvZTcaMAxB2AKJ8wpDgQJg5WwkpmYrVFB4%3d
  19. kevin gilmore
    and then you have to change the driver power supply to +/-350
  20. kevin gilmore
    yeah, there is about 5 volts of offset, no biggie board posted there are 3 resistors in series for the feedback and its 890k total on the board. no, you definitely should not try to use this as a dual voltage supply because only one side is regulated. like this http://gilmore.chem.northwestern.edu/circlotronhvpowersinglenew.jpg
  21. kevin gilmore
    should you actually find music that will drive the amp at the speeds necessary, the output stage will drop out of class A and go into AB.
  22. kevin gilmore
    this is the new power supply schematic. i like it much better than the previous version. new board soon http://gilmore.chem.northwestern.edu/goldenreferencehv900new.pdf runs on much less voltage, so for the dht amp running at 50ma, less heat also less noise than the old version, and no pile of zeners
  23. kevin gilmore
    try not to do it hennyo style!
  24. kevin gilmore
    its low voltage, so standard silicone pad is just fine. takes up about 25th, so no room necessary
  25. kevin gilmore
    has to suck the heat from somewhere the heated heatsinks cause airflow
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