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Also see : POT4a and POT4b

POT4 Power Supply

POT4 Header Pinouts

Voltage Reference

Discussion of the voltage reference.


top side
bottom side
  • POT4 is a green PCB with white silk screen.
  • Dimensions 1.75" x 0.85"
  • Two mounting holes (diameter = 0.125"), top side clearance > 0.25"
  • The color of DL1,DL2 indicates the input configuration of the board

Led Indicators

  • (DL1, DL2) : A pair of single LEDs indicate the present of power. These LEDs are aligned with the power input to the boards.
    • RED : configured for potentiometer inputs (#1-2)
    • GREEN : configured with bridge inputs (#3-8)
  • DK1 : The intensity of this dual RED/GREEN LED indicates the voltage of the "position signal".


  • JF1 : 3 way jumper used to select source that drives that "Position" output. The signal source may be one of the following:
    • Instrumentation amplifier output
    • 2nd order low pass filter output
    • 4th order low pass filter output
  • JC1 : selects the "Shield" header signal source and is specified at assembly time. Signal sources include "GND", "COM", or "REF-".

Assembly Variations

POT4 can be built for either potentiometer input or bridge input. There are also several optional circuit modules.

  • boards #1, #2 : fully built with lowpass filters, differentiation and configured for potentiometer input. These boards use the LT1167 with gain G=1+49.4K/RA1.
  • boards #3, #4 : minimally built for strain gauge bridge input. These boards use the INA122 with gain G=5+200K/RA1. Opamp LM324, 100K trim pot
  • boards #5 - #8: built for strain gauge bridge input and are minimally built with 2nd order LP filter. These boards use the INA128 with gain G=1+50K/RA1. Opamp LM324, "503" trim pot
  • board #9 : same as #1,#2 with INA128, Gain 1+50K/RA1 - populated for POT board
  • 8-1-05 : board #9 returned for repairs.

Design Files


Bill of Materials

Bill of Materials


POT4 Datasheets