0-10v Servo Control with 7i76E

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03 Aug 2023 08:41 - 03 Aug 2023 09:06 #276828 by besriworld
Hi, stupid mistake. I had to change the sign/direction of the feedback. But there seems to be a problem with my board. There is noise in the analog signal. And with 1000 revolutions per minute and without a pid regulator I get spindle-vel-fb-rpm-abs 1005-1010rpm

should I filter the analog signal?

 

What do you think of the scheme?  I can also upload a simulation ?
In simulation it's good, but in real life it's not good :)

Maybe I should add a capacitor in parallel with the resistor R28 ?
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Last edit: 03 Aug 2023 09:06 by besriworld.

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03 Aug 2023 13:06 #276834 by PCW
Replied by PCW on topic 0-10v Servo Control with 7i76E
I think the filter is not needed, also feedback is likely not needed either
as speed variations of a few % will have no significant effect on machining
or spindle synchronized motions as long as your encoder resolution is greater
than say100 PPR.

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03 Aug 2023 15:35 #276839 by besriworld
I have big plans for the lathe :) . I will add another spindle in the future. This one should work as a C axis. Currently the resolution of the servo motor is 2048x4 = 8192 . I will add an additional encoder connected to the spindle with gear 2:1 or 3:1 ( 8192x 2 or 3 ).

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02 Mar 2024 21:09 #294948 by besriworld
Hi, I can't clear the output voltage ripple ...Does anyone have a photo of the +-10v signal with the oscilloscope.
What can I improve on the scheme?

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02 Mar 2024 21:30 - 02 Mar 2024 21:44 #294951 by Mecanix
edit; ignore that, just noticed the tiny _invert label
Last edit: 02 Mar 2024 21:44 by Mecanix.

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02 Mar 2024 21:39 #294954 by Mecanix

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03 Mar 2024 12:10 #295022 by besriworld
The problem is that if I put a big capacitor and a resistor, I will add a big delay. I want the spindle to also work as a C axis for milling. I don't know what's wrong. Does anyone have a diagram of the solution that is in MESA card? Or a picture of the output with an oscilloscope?

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03 Mar 2024 14:46 #295053 by PCW
Replied by PCW on topic 0-10v Servo Control with 7i76E
Here is the analog output circuit of the 7I97
Note that this uses offset PWM (no direction signal)
It does need an enable signal.

Note that the power for the LCX04s come from a
3.3V reference supply

 

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03 Mar 2024 15:04 - 03 Mar 2024 15:07 #295056 by chris@cnc
I check this on my noise nightmare. 10V Signal and out at 4K and 8K.   0,4V max
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Last edit: 03 Mar 2024 15:07 by chris@cnc.
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03 Mar 2024 20:46 #295082 by besriworld
Thank you for sharing! After simulating the circuit, I changed some resistors. Now I have a faster reaction. It seems that the main problem in my scheme is that I use a common power supply. I have 35mV (Pk to Pk) ripple in the 5V power supply. Do you have any ideas for reducing in power supply ripple or other easy modification in board?

 
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