Spindle drive: potentiometer replacement

# Thread: Spindle drive: potentiometer replacement

1. ## Spindle drive: potentiometer replacement

Hi,
My breakout board produces 0-10v analog out for spindle control.
My spindle driver board only has a potentiometer that uses 0-5v to control the spindle speed.

What is the best way to have my breakout board replace the potentiometer to control the spindle speed?

Is there a board that translates the 0-10v of my breakout board and translates it into 0-5v of the spindle drive ?

I also assume that I should not directly connect the GND of my Breakout board to the GND of my spindle drive.

Is there a circuit that does both of these things?

Thank you!

2. ## Re: Spindle drive: potentiometer replacement

You won't be able to use the analogue 0-10v afaic.
Does the breakout board have a PWM option instead?.

Do some research regarding PWM signals and various PWM to analogue converter boards. You may come across a 0-5v board that's useable.
PWM output from bob - PWM to analogue converter - converter to spindle.
That's all I've got on this subject.

Actually I just wondered something.
In my Mach3 spindle settings I recall I can set the maximum pwm output from 0-100%.
I wonder if I set it to max of 50% wether it would only put out 5v from my analogue?.
Might be worth looking into with a voltage probe/meter if yours has that setting as well.

3. ## How do spindle drives 0-10v speed control inputs work?

Most spindle drives have an analog input (0-10v) to control the spindle speed. (Vso,Vi,Agnd)

I see people connect the ground from their breakout board (digital GND) to the ground of the spindle drive (analog ground).
Is that correct? Aren't these different ground planes?

For digital circuits we use ooto couplers to isolate them. How is the 0-10v analog input of the VFD isolated from the breakout board?

How does the analog input circuit of the VFD look like ?

Thank you.

4. ## Re: How do spindle drives 0-10v speed control inputs work?

Originally Posted by rschwarz
Most spindle drives have an analog input (0-10v) to control the spindle speed. (Vso,Vi,Agnd)

I see people connect the ground from their breakout board (digital GND) to the ground of the spindle drive (analog ground).
Is that correct? Aren't these different ground planes?

For digital circuits we use ooto couplers to isolate them. How is the 0-10v analog input of the VFD isolated from the breakout board?

How does the analog input circuit of the VFD look like ?

Thank you.
What VFD Drive are you using and from what control is your 0-10v coming from

5. ## Re: Spindle drive: potentiometer replacement

I used a 10 turn potentiometer 2k ohm to set the output voltage on my machine.
Attachment 464201

This worked for my machine because both the VFD and BoB have isolated power supplies, both grounds are isolated so it was safe to connect the two ground wires. If you have tested and found no voltage AC or DC between the two ground wires and are still unsure you could add a small fuse ~0.5 amp or less before you apply power (optional). Test the grounds first before you do any other wiring, you dont need to cut or change anything, just test.

The Bob I am using runs off of 12-24 volts and the 0-10 volt output comes from that supply, my VFD has its own isolated low voltage supply also, this is typical of most modern control parts but I still tested both grounds for AC and DC voltage before I made the connection.

Disclaimer: If you are unable to properly test for ground voltage or know detailed wiring for your machine, this design may not work for your setup or may damage some or all parts. I take no responsibility.
Attachment 464205

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