Hi guys
Please give me some advice on the attached opamp schematic im trying to use a 0-3.3v pwm signal to control a spindle which needs 0-10v analog voltage, ive connected on breadboard but im only getting high or low volts nothing in between?
Thanks
Hi,
From your diagram, you have a high pass filter on the output, it should be a low pass filter.
This link may help.
Tom... 
@Undermentioned
What is the PWM frequency?
Your resistor values for the feedback are low. I'd go up a factor of 10.
How did you choose the values of 4k7 & 150nF for the filter?
What is the PWM coming from (exactly which "arduino"?)
What is the PWM frequency?
What load does the "spindle" put on the output ? - you may need to buffer it.
This explains what I did to get a smooth analog value - using a high frequency PWM and a simple RC filter
See if this helps:
Handbook of operational amplifier applications
or this:
Why not do the low pass filtering on the MCU output before the Op Amp? Think I would use a 10 or 12 bit DAC with 5V reference, then amplify to 10V.
It is much easier and more accurate to use a 10V DAC than PWM and some op amp circuitry.
+1, I wasn't sure there were 10V+ models easily available to the hobbyist.
Depends where you live.
Back in the '70s and '80s when most of my work was with analog, I had pretty wide knowledge of devices from Burr-Brown, AD, National Semiconductor, etc., But that's all faded away. 
+1
The output voltage of this circuit depends on the load you hang on the output.
If you filter first, and then amplify, you don't have that problem.
Leo..
Hi,
See post #2 .
Tom.....
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