Im using an arduino to control some of the features of my DIY Amplifier, i would also like to be able to read out the current voltage of my amplifier. For this feature i where thinking of using a voltage divider to get voltage down to a readable level. But, i don`t wanna connect my noisy digital ground to my quiet analog ground, is there anyways to separate this and still be able to use a voltage divider?
What would happend if i used a 1k resistor to separate it?
Common practice is to attach all the grounds together as long as you don't have a short. I have attached the GND from two 9V batteries directly to by arduino's ground. The 18V went to an arduino-controlled mosfet, which operated no problem. If you are worried, just put a diode on each ground like this:
Digital Ground----->|------
|--- GND
Analog Ground----->|-----
Very easy to setup, so I highly reccomend it. (The link is for a 50A sensor, if you need to measure smaller currents, it would be better to find a sensor with a lower current rating)