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Hello I'm Jo from south korea.
I'm not good at English, so I appreciate it if you understand me.
I'd like to make ECG module with INA126 and Arduino Uno.
Arduino Uno can provide only single supply as zero to 5V.
So I wanted signal that swings 2.5V.
Before I make module, I tried to test INA126.
When I tried to test with dual supply, It worked well as I expected.
But with single supply, It didn't work.
The input was +/-100mV 1Hz sine wave, but I can't understand why the result was like that.
Q. Could you explain the reason why? and if the schematic is not proper for module, can I get some schematics related single supply?
Thanks for your time.
Hi Seonjo,
The issues are INA126 has a minimum gain of 5. Under a single rail supply from 0-5V, your input common voltage is between 1-3.1V approximately. You are not going to get 2.5V swing with gain of 5 V/V, see the attached image. This is instrumentation amplifier, and you may have to use dual supply rails. Enclosed is the Tina Simulation.
/cfs-file/__key/communityserver-discussions-components-files/14/INA126-03272020.TSC
You may try with INA128, INA129 with gain of 1, but it may still be difficult to get 2.5V swing out of a single voltage rail.
If you need further assistant, please let us know.
Best,
Raymond
