Pololu G2 current sense output for Spindle load meter?

I have used the OPA series a fair bit for things like load-cell amplifiers.
It should do the trick.

okay before i buy an OPA, i have a CA358e from RCA laying around and it should be an opamp but i only find the datasheet for CA358 or CA358a (the datasheet = 4donline.ihs.com/images/VipMasterIC/IC/H...2B6ED9A73243A3159BB0 ). does anyone know if i could use the CA358e?

edit: which opamp would be best suited for my project? i dont have much knowledge when it comes to such things

thanks

The CA358 seems to only swing from 0 to Vcc -1.5V. That is probably OK here as the DAC input is 3.3V, so for a 5V supply that is about right.

Why not try it and see? I would breadboard it first with a variable resistor to set the gain, then maybe switch to a fixed resistor when deploying it.

okay thank you, i will see what i can do

i breadboarded it but it doesnt seem to work (no reaction to when i try to stall the motor, except when i touch the motor housing i see a little bit, but the Current sensing output does definately output correct). Either the opamp is defective or i wired something wrong.

5 V to the + pin (, ground to the - pin (4), current sensing pin to non-inverted-input a (3) and output a (1) to my oscilloscope (negative of the oscilloscope to ground)

edit: which opamp would be best suited for my project? i dont have much knowledge when it comes to such things

i guess one that has a maximum output of 3,3v, but which one i dont know

An Op-amp always needs a pair of resistors to set the gain.
Nothing will happen without those.

Okay i think i got it working. I wired the opamp according to this site: www.learningaboutelectronics.com/Article...g-op-amp-circuit.php and now i can see change with my oscilloscope. Is it normal that it is not a straight line but zigzag like? Probably can be filtered on the analog in i guess.

Thank you for your help

If the input is smooth then the output should be smooth. It really should just multiply the input voltage by a gain factor.

yeah i looked at the current sensing output and it is zigzag aswell (probably because of the pwm signal)

Probably something most easily handles with a HAL lowpass.