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JoaMat

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Everything posted by JoaMat

  1. JoaMat
    Just finished my morning coffee. Seems to be an interesting day. Thanks a lot Kerry.
  2. JoaMat
    As I understand LT1021 is used in shunt mode in GRLV. From datasheet I get the impression that the 5 volts version of LT1021 is not meant to be used in shunt mode. As I recall one builder once tried a LT1021-5 in a KGSShvPSU without success.
  3. JoaMat
    After a second thought I’m beginning to believe that it shouldn’t make any difference at all. After the diodes the “output” should be the same after swapping the leads from transformer, or?
  4. JoaMat
    Thanks. This is a very long shot but what happens to the hum if you swap one of the AC from transformer to rectifier diodes (HV900). Will there be a change in hum if the AC to the two “rectifier bridges” are in 0 degree or 180 degree phase?
  5. JoaMat
    Isn’t that an earlier PSU version with the long zener string?
  6. JoaMat
    LTspice indicates a need of another 3 V unregulated. Plus more diode switching noise. Still a golden reference device or is it a silver line thing?
  7. JoaMat
    Thinking loud. What if a simple CCS north of the 9 volt Zener as below? Will certainly make a tiny smd version layout looking cleaner.
  8. JoaMat
    Milled this today – negative regulator. Shot by USB camera approximately magnitude 20. Using a 15th end mill, minimum clearance between pads, traces etc. is 16th. There are 5 vias 12th and they actually hit the bottom pads quite accurate. CNC machine is a fantastic gadget
  9. JoaMat
    Did this today. Positive golden reference regulator. I managed to make a Kerry device in my kitchen but I think he is pushing the envelope now. I’ll try to make negative regulator as well and if this succeeds I’ll put them in a T2 PSU. Dark picture so you can see the small red LEDs on the board. Hope the small GRLV hit the market soon.
  10. JoaMat
    Great work! Reason for KST42/92 replacing PBSS4140DPN? - need for higher collector-emitter voltage?
  11. JoaMat
    470R resistor, isn’t that the grid resistor? If so, is 2 W really necessary? From simulation I get some 2 – 4 mA through the resistor. In my Grounded Grid with mostly surface mounted devices I use 0805 chip as 470R - 1/8W and they seem to work.
  12. JoaMat
    Law of nature. You always need a sufficient transformer.
  13. JoaMat
    Oh, sorry. Too much Amarone. Happy New Year to you all!!!!
  14. JoaMat
    If the pot you are asking about is same as RV3 in schematic a few post earlier then; With 240R as in the original DIY T2 the current theoretically is 5.1 mA. Adding 10K pot and 1K resistor with pot at mid position give 5.2 mA each CCS. Pot at end point gives you 5.1 respectively 6.2 mA. Just increasing the pot value won’t change the “current range”.
  15. JoaMat
    I’m very much interested.
  16. JoaMat
    Happy Birthday!
  17. JoaMat
    Putting something like cpc1117 cross C2M1000170D gate and source would that be usable as an emergency stop? Alternative cross gate and output (before 5.1k resistor).
  18. JoaMat
    Electrolytics in red…. ….done today - probably on its way to trash can.
  19. JoaMat
    Is the jump up to +250 volts not normal behavior? That's what my Carbon does, 500V rails and my multimeter catches +330V before slowly down to 0.
  20. JoaMat
    All right, I rather prefer to open you gerbers in Proteus and save them as pdspnl files – works great. Thanks a lot for all work you have done!
  21. JoaMat
    I use Proteus v8.5, isn't that the software you are using? I guess you are able to open gerbers you made yourself. Can it be some software setup I've missed?
  22. JoaMat
    When I try to open gerbers, probably of newer version, in Proteus I get warning about “Bottom SMT Paste Mask” and file won’t open. After deleting corresponding line in the readme file it opens nicely in Proteus. What might the reason be that it won’t open without delating that particular line in readme file.
  23. JoaMat
    Early stage work on a Circlotron (Aug. 2015). The prototype exploded during initial take-off roll.
  24. JoaMat
    This is how the small board with trimmer and resistor looks like. I do think the T2 amp board by Kevin is a very good one. Easy to build, just put the right component in right position, solder properly and then you are done. If something goes wrong it’s possible to work on the board. And it's also a terrific board for experiments, tests, modifications…...
  25. JoaMat
    Nice, manual control seems to work well.
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