Electrode Module 2
This is an (untested) improvement upon Electrode Module 1 and implements the "Signal Processing Module" from circuit 5.1 and circuit 6. Essentially it calculates the difference between the voltages at the "in1" and "in2" pins, after applying a high-pass filter through C1/C2, and a pull-up/down through R1/R2 towards Vref to base the signal around the center.
- C1: 100pF capacitor, 0805 package
- C2: 100pF capacitor, 0805 package
- C3: 100nF capacitor (exact capacitance not very important), 0805 package
- R1: 1MOhm resistor, 1% variance, 0805 package
- R2: 1MOhm resistor, 1% variance, 0805 package
- R3: 1kOhm resistor, 1% variance, 1206 package
- INA128: Texas Instruments INA128 instrumentational amplifier, SOIC/SO-8 package
The "out" pin goes directly to the Arduino ADC (or perhaps through a multiplexer)
The redundant Vref/GND/V+ pins can be used to wire multiple of these in a tree network topology, where only the first board needs to be directly connected to the power module.
- Dimensions: 20 x 16mm