Talk:DreamTeam/Brainduino
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what is value of c33? 50 pF or 1 nF ?
Op amps ... OPA2111 - what gain? what values for R27, R23, R24 ? (also R28, R25, R26)
R27 should be 2K ohms R23, R24 -> 100K ohms
cf instrumentation amp
2nd Stage AD8422 Instrumentation amp with gain resistor 2(10 kΩ + RREF)/(20 kΩ + RREF) http://www.analog.com/media/en/technical-documentation/data-sheets/AD8422.pdf In figure 56, you will see that an op amp is used to input to the VREF pin.
3rd stage Low-cut (aka high-pass ) filter and DC offset to 3rd Stage OP2177ARMZ ( IC1B Ch1 and IC1A Ch2 )
4th Stage IC3D>IC3C Ch1, and IC3A>IC3B, Potentially considered a two-pole high-cut(aka low-pass)