Part Number:INA326
Hi
Im currently using the INA326 for an EMG filter. I see that the suggested schematic has a filter in it. When trying to calculate the frequency it didn't correspond tho the 1kHz it says. Here I have a first question:
1) How the filter was calculated and how can I re calculate it to hava a cut-off frequency at 400Hz??
Question 2:
I was having a problem and the suggested answer was the lack of the path for the bias current. I put some resistors in it and the output remained at ~-800mV but this time it was stable. Im guessing this is normal no? to have an offset caused for the electrodes. Am I right? I used 47K, 1M and 10M and the behavior was the same...
I was thinking on changing the INA326 for the INA128. So here come questions 3 and 4
3)Does the filter at 1kHz can be applied to the INA128? I mean... can I use the same schematic as the one for the INA326?
4)I tried to do a High Pass filter to remove the offset by adding a capacitor in series with Rg (something like image below)
But when measuring with the oscilloscope, the output signal still had the offset... Why it didn't work as a high pass filter? or did I miss something?
Thanks for the help!