From DIDEAS Wiki
Discussion of the voltage reference.
- 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
- (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-".
POT4 can be built for either potentiometer input or bridge input. There are also several optional circuit modules.
- Detailed POT4 Gain by serial #
- 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.
- Q: How to adjust the gain?
- Q: What is pinout of the headers?
- Q: What are the characteristics of the voltage reference?