Why INA333 May Not Show EMG

INA333 is a precision instrumentation amplifier, but a visible EMG waveform depends on the whole front-end system, not the amplifier chip alone.

Common Reasons

• Input bias path is missing or unstable.
• The output midpoint does not fit the ADC range.
• Gain and filtering are not matched to the expected signal.
• Electrode contact is poor.
• Power noise or ground coupling dominates the tiny EMG signal.
• The ADC sampling setup hides or clips the useful waveform.

Practical Debug Order

1. Confirm power rails and output midpoint.
2. Confirm the ADC range and input mode.
3. Use wet electrodes for the first test.
4. Try battery power and move away from chargers.
5. Check whether the signal changes during contraction.

If you want a ready-to-test path, start with AAW sEMG Flex and the Quick Start.