Having played around with this product for a weekend, I am left wondering how it can really be useful for measuring low currents, when no matter what I do, the output is rather unstable. https://www.sparkfun.com/products/8883
I have set the vref so that around 3 volts output is 0 Amps - when no current is flowing through the sensor.
I have set the gain to the lowest possible setting - 4.7.
But, the 3 volt output varies between 2.95 and 3.20 volts when no current is flowing through the sensor.
The output voltage *does* increase as expected when measuring between 0.1 and 0.5 amps, with gain at 4.7, there is a reasonably small voltage increase.
But, the problem is that the baseline 3V output is just too unstable.
So first question is:
If this breakout board is designed for measuring low currents, how do people actually achieve this with such unstable output?
My second question is:
I think this breakout board with configurable filter capacitor will probably work better.
Am I correct in thinking that a larger capacitor value will reduce the bandwidth, and make the output look more stable?https://www.sparkfun.com/products/8882
Is it also correct to say that reducing filter bandwidth gives more accurate outputs, when measuring larger current?
If the above is correct, my third question is:
Can anyone point me to some docs that explain what filters and bandwidth are, in the context of... perhaps analog electronics?
I know what a filter is, and I know what bandwidth is... I just haven't grasped the concept of why reducing filter bandwidth is better when measuring larger currents.
Thanks in advance.