Distortion - BOB-09816 operational amplifier breakout board

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1

Bought three Sparkfun BOB-09816 op-amp breakout boards for use in a noise detection project.

I am having a problem getting them to correctly amplify signals below about 80Hz.

With an input of a 1 volt peak to peak sine wave and the board’s potentiometer set so that the output of the board does not saturate, I get distortion at the positive and negative peaks as the signal frequency is reduced from 100Hz down to 50Hz. The distortion kicks in at around 80Hz. Above 100Hz, they behave as expected.

Any help would be appreciated.

2

With an input of a 1 volt peak to peak sine wave

The first amplifier of the two on the breakout board has a fixed gain of 10, so it is probably overloaded, especially if you are using a 5V power supply. See schematic of the first stage below.

I suggest to reduce the amplitude of your signal source to 100 or 200 mVpp for tests.

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