Hello everyone. I recently got a couple of sensors (Weak signal amplifier LM358 and AD620 Instrumentation Amplifier Module). Now I wonder how I can improve the measurement accuracy of the ADXL335 accelerometer using these sensors? My plan is to measure only one axis (let's say Z-axis).
Has anyone worked with such sensors before, are there any examples of how to use them?
Firstly an amplifier is not a sensor. A sensor senses something, an amplifier amplifies an existing signal (voltage usually).
No you can only reduce accuracy and precision with an amplifier, but usually the source of the signal is the limiting factor and most amplifiers have good performance (like very low offsets, distortion etc).
What an amplifier can do is increase the signal level so that it spans the full range of your ADC allowing maximum ADC resolution to be taken advantage of. But in some circumstances the ADC will remain the limiting factor and one with more bits might be needed.
So in that sense the accuracy of the system might be increased, but you can't make the sensor any better, just improve the A/D conversion performance.
Never worked with an ADXL335 sensor, but from the Adafruit website...
"The analog outputs are ratiometric:"
So which Arduino are you using.
If it's not given, then we assume an Uno.
Then it's logical to switch Aref to EXTERNAL, and connect the 3.3volt supply of the ADXL335.
Warning: must have analogReference(EXTERNAL); // in setup, otherwise you could fry the Uno
Other Arduino boards will have other solutions.
Leo..
Those amplifiers won't do anything to improve the accelerometer accuracy, but calibrating the accelerometer and averaging data points certainly will.
Best overview on accelerometer calibration: Tutorial: How to calibrate a compass (and accelerometer) with Arduino | Underwater Arduino Data Loggers
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