Motor Fader Slow Speed Stutter

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tomas1808

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Nov 27, 2009
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187
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Montevideo, Uruguay
Hi,

I bought a bunch of TKD motorfaders (MF-914-B10K-10V) and I built this PID circuit to start tinkering with fader automation stuff.

This is my first time dealing with PID circuits. I used a signal generator for the target signal.

I managed to tune the circuit and get the fader moving smoothly and without overshoot as long as the target is moving quickly.

As soon as I decrease the frequency on the signal generator, the fader gets all stuttery and jumpy. I am not able to get the thing moving smoothly.

I have a bunch of these faders, both used and new, and the problem is the same with all of them, so I don't think the faders are the problem.

The motors are not the coreless version so they have more friction (as I understand).

I dont think the Integral part of the circuit is working. My intuition is that the integral component is more for longer term error correction, am I right? Or might this be the key to get it running smoothly?

Any ideas?

Thank you!
 

abbey road d enfer

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Jan 22, 2008
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Marcelland
First I would try to make the P part working. For that I would fix the deadband issue with the output circuit. I would replace the LM324 and the Darlingtons with a TDA2040 or an equivalent audio amp.
 

tomas1808

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Joined
Nov 27, 2009
Messages
187
Location
Montevideo, Uruguay
Thanks! I am a newbie, can you explain what you mean by deadband issue in this case? You mean the portions of the travel where it gets stuck for a sec and then jumps to the next? Can that be fixed with the P part only?

Also, what would be the rationale behind changing those components?


Nevermind, I see what you mean.
 
Last edited:

tomas1808

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Joined
Nov 27, 2009
Messages
187
Location
Montevideo, Uruguay
Thanks JR, I will look into that.

BTW, I noticed the fader only moves slowly and consistently when applying at least 1.8VDC to the motor. Would it make sense to make the output start at 1.8VDC when the waveform goes up and -1.8VDC when the waveform goes down? In other words, remove the voltage range where no movement is made.
 
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