We have a sensor giving out a signal between -10 V and +10 V, and a signal acqusition device that only accepts voltages between -2 V and +2 V. So we need to scale down the signal into the smaller range. As possible solutions I have identified:
A. Use a voltage divider
Following the information in this page: https://learn.sparkfun.com/tutorials/voltage-dividers, I could use two resistance, R1 = 5000 Ohm, and R2 = 1200 Ohm.
I am not sure what am I allowed to use a Ground. Both devices (sensor and acqusition) have a ground connection, which are connected to each other. Can I use this common ground as for the ground of the voltage divider ?
The impedance of the signal acquisition device is specified as 1 MegaOhm. Why is this value given at all? Should I include it somehow in my voltage divider calculations ?
B. Buy some off the shell device
I have seen some voltage down regulators, but they appear to only address power applications. I assume they are too noisy to be used for sensor read-out. Furthermore, there appears to be no device offering downscaling negative voltages.
- Are there commercial voltage downscaling devices made for sensor reading ? I am not familiar in this area and I might be just ignorant of a family of devices that already does this in a plug an play manner.