electrical precision measure

[lucian_v]

Hi all,
I want to build a personal project which require to measure some force sensors which have 4 wires. 2 of them are for power the sensor with 8v (i am using an external power source for them) and 2 wires are giving the output in milivolts . For example sensor measure 100kg and each milivolt is 1kg.
I need your help on achiving this using rasp. I am thinking maybe i need an external device for this or can i do that only with rasp?
I want also mention that i would like to read sensors 10 times per second ...

Thanks in advance

[Laurens-wuyts]

For reading the voltages you'll need a Analog digital convertor, but for measuring millivolts you'll need a very precise one.
You'll also in some way need to reduce the 8V to 3.3V or 5V for the Analog digital converter. You can do this by using a simple voltage divider.
10 times a second is for a RPi (or every other microcontroller) no problem.

Laurens

[lucian_v]

Thanks a lot for answer.
Can you point me to a suitable dac for my project?

[KLL]

if you use a good amplifier
http://www.ti.com/lit/ds/symlink/ina125.pdf
you can use a normal ADC or even arduino ( connected by USB...) for it
http://edg.uchicago.edu/tutorials/load_ ... ematic.png