PWM Controller Guidance

[james211]

So I'm working on a project that uses a manual pot controlled PWM controller. The controller needs to be able to slow a 12v motor driven peristaltic dosing pump. I've run tests using several different controllers found online and this one in particular works very well!!

What I don't like about that controller is its size. So here is my question, I have a few of these laying around, but they don't do well on the low end of the motors speed, its not as consistent as the previously mentioned controller. So I'm curious what I could do to make the dalewheat controller work better on the low end? I have spoken with Dale but unfortunately he doesn't have time to help me out. He did give me the OK to do what I want with his controller and he also gave me the eagle file.

When I test the motor under load at low speed I get 4v @ 0.2A, and at high speed around 10v @ 0.2A. Let me know if you need any additional info to help me out with this.

I've also attached the schematic and parts list to the dalewheat dimmer.

 

[HANKMARS]

So I'm working on a project that uses a manual pot controlled PWM controller. The controller needs to be able to slow a 12v motor driven peristaltic dosing pump. I've run tests using several different controllers found online and this one in particular works very well!!

What I don't like about that controller is its size. So here is my question, I have a few of these laying around, but they don't do well on the low end of the motors speed, its not as consistent as the previously mentioned controller. So I'm curious what I could do to make the dalewheat controller work better on the low end? I have spoken with Dale but unfortunately he doesn't have time to help me out. He did give me the OK to do what I want with his controller and he also gave me the eagle file.

When I test the motor under load at low speed I get 4v @ 0.2A, and at high speed around 10v @ 0.2A. Let me know if you need any additional info to help me out with this.

I've also attached the schematic and parts list to the dalewheat dimmer.

How critical is receiving an exact dosage volume? What dosage is delivered at what frequency? Example; 1ml per second. 10ml delivered every 10 minutes. Etc.

 

[Minder]

This one is quite comact.
http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm

 

[Bluejets]

Part of the problem with low end performance is there is no feedback to compensate the low end speed.
Either use a more complex circuit with feedback of some description or use a gearmotor running at a much higher speed.

 

[crutschow]

Since the PWM is generated by an ATtiny13A micro, it's not possible to know what it is doing inside.
Do you have an oscilloscope to look at the signal waveforms?

As a shot in the dark, you could replace the ATtiny with a discrete PWM circuit.
I have a typical circuit for that using an LM339 comparator IC that generates a 0-100% adjustable duty-cycle.
Would you be interested in trying that?

 

[dave9]

Topic is from 2014, and the only post by this member... james211 has probably moved on by now.