Wednesday, July 31, 2013

KGSSHV amplifier

An all solid-state electrostatic headamp design by Dr Kevin Gilmore.

There are 2 options for the KGSSHV. Onboard or offboard heatsinks.


Schematics:

Amplifier with Servo:
http://gilmore.chem.northwestern.edu/kgsshvproductiondual.pdf

Mini Power Supply:
http://gilmore.chem.northwestern.edu/kgsshvps8g.pdf

Latest silkscreen:

  • Onboard:
Board dimensions(mm): 185 x 123


  • Offboard: 
Board dimensions(mm): 183 x 99


  • Power supply:
Board dimensions(mm): 176 x 167



Latest BOM:
Important notes:

There are 2 ways to build the KGSSHV. Either one with 450V or 500V power supply. 

For 450v version, these are the requirements:
  • Power transformer specs: Pri: 110v/220v. Sec: 2x 420v/130mA, 16v-0-16v/500mA
  • PSU board:  Use 4x 440K resistor ; Total zener diode string is 500V (150v-150v-200v) ; Populate ALL the parts, including the voltage multiplier.
  • Amp board: Use either 2x 2SA1968 (recommended) or 2x IXTP01N100D.
For 500v version, these are the requirements:
  • Power transformer specs: Pri: 110v/220v. Sec: 2x 450v/130mA, 16v-0-16v/500mA
  • PSU board:  Use 4x 487K resistor ; Total zener diode string is 550V (150v-200v-200v) ; DON'T populate these parts in the voltage multiplier section: 0.22uf/1kv cap next to the bias output, 2x 4007 diodes, 15k and 787k resistors, jumper the 0.22uf/1kv cap next to the 300k resistor.
  • Amp board: Use 2x IXTP01N100D only. The 2SA1968 is not up for 500V operation.
Power Supply build notes: 
  • Fuse ratings: it is recommended to use fuses for both Live and Neutral. For 110-115v mains voltage, use Slo-Blo 2A. For 220-230v mains voltage, use Slo-Blo 3.15A.
  • Power transformer can be custom ordered from either Sumr.com (Canada) or Toroidy.pl (Poland). Toroidy does offer 2 kinds of transformer, standard one or audio one with selected and measured core, electromagnetic shield. They do have more reasonable price and shipping charge.
  • Use either 6x 2sa1486 with the 270v zeners unpopulated or 6x ksa1156 with the 270v zeners populated. Also, either 4x 2sc3840 or 4x ksc5026m.
  • 10m90s devices need aluminum oxide isolator. Also, MUST use nylon screws.
  • FQPF8N80C devices themselves have isolated tabs so no need to use anything with them. Just apply a bit of heatsink goot and whatever screws are fine.
  • Elevate the high wattage resistors (15R/2w and 240k/2w) for better heat dissipation.
Amplifier build notes:
  • Absolutely make sure you connect either Local or Global Feedback jumpers.
  • Adjust the balance trimpot in middle.
  • Adjust the offset trimpot to maximum.
  • Use aluminum oxide and PEEK screws (recommended) wherever needed.
  • Connect the Servo jumper, if needed.
  • Measure everything for short.
Wiring Sheme:

Here is the wiring scheme, superbly drawn by johnwmclean (thanks, John!).
Make sure using 600v teflon wires here, except for signal path.

https://docs.google.com/file/d/0B4NVeoQi85GgOTdvOGpxc1hyRFU/edit?usp=sharing

8 comments:

  1. Don't forget about the jumper for skipping the voltage multiplier? in the case of the 500V version.

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  2. Forgot that so I updated the info. Let me know if I missed something, thanks for heads-up :)

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  3. 115v= 2A fuse
    220v = 3.15A
    Shouldn't this be other way around?

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  4. @Lil Knight -
    Great job with the documentation!
    About time there was a compendium on KG's latest works.

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  5. http://gilmore.chem.northwestern.edu/kgsshvproductiondualmot.pdf

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  6. please update the BOM to reflect the need for isolated HV diodes, part # 511-STTH512FP. Don't use the non-isolated parts that were valid fro the older version of the PSU.

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  7. This comment has been removed by the author.

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  8. Does anyone know if there are board layout suitable for etching own boards for this wonderful amp? All I find is silkscreens and jpgs with all layers on top of each other.

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