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.


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 :)


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

Last modified 21 months ago Last modified on Nov 9, 2020, 4:26:21 PM