I recently bought a ADS1115 ADC to use with my raspberry pi. It's getting signal from an amplifier, and I've been seeing this strange 5.5 Hz sinusoid (as noise).
As seen in the picture above, its about 5.5 Hz, roughly sinusoidal. A few observations:
- Noise (5.5 Hz sinusoid) is present in my signal when ADC is connected to amplifier
- When ADC is disconnected and input floating (with wire), noise is present (still 5.5 Hz sinusoid, less in amplitude).
- When I ground the ADC input, I don't see the waveform
Any idea on what could be causing this? It's so low frequency and I'm totally stumped... I'm trying to figure out the source and then how to get rid of it... would appreciate any ideas!