wiki:TubeBiasMonitor

Version 15 (modified by Eric Hazen, 2 years ago) (diff)

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Built a board. 4x INA128 instrumentation amp input plus 2X single-ended inputs, all powered on 24V.

INA128 can run up to 36V, LM358 up to 32V. SRPP offset voltages are around 45V or higher, so maybe with the divide-by-two inputs it would be better run on 28V or even 30V.

11/8/20

Stuffed board, trying to test. Completely screwed up the programming connector. It's a 2mm pitch numbered wrong. Managed to wedge in a 2x3 header, can maybe fix the pinout with a knife.

  MISO (18) -- 1   2 -- VCC
   SCK (19) -- 3   4 -- (17) MOSI
  nRST (1)  -- 5   6 -- GND

Now I can at least download blinky light firmware :)

Box:

INAs would measure the four bias voltages. Additional channels would measure the DC offset from GND of the cathode circuits on each side.