POT4 GAIN
From DIDEAS Wiki
POT4 Gain Adjustment:
To change the instrumentation amp gain change the value of RA1 on the back side of the board. This component is a 1206 resistor and thus is somewhat larger than the others. The text "gain" is located near the RA1 label.
The instrumentation amp gain equation is depended on the amplifier used:
- INA128 : G = 1 + 50K / RA1
- INA122 : G = 5 + 200K / RA1
- LT1167 : G = 1 + 49.4K / RA1
For a gain of 500x change RA1 to 100.2 ohms. Do this either by removing the existing RA1 or probably more easily stacking a 2nd RA1 on top of the existing RA1. The gain of 500 can be had with a 499 in parallel with 125 ohms.
