Here's the thing.
Everything seems to be opposite of what I read.
I need a parastaltic pump to deliver 3-70 ml/min.
I thought pwm and duty cycle would be the way to go.
But it's less flexible than straight dc supplied by my bench power supply.
I need the motor to start at lowest rpm possible to get the 3ml.
The power supply dc starts the 1/2 amp brushed dc motor at about 1v.
PWM (20khz) it doesn't start untill 3.5v ave.(measured on vom), and its turning too fast at that point.
It even seemed better at 490hz, which I accidentally programmed in at first.
I can get more rpm with the pwm, but low speed startup seems very allusive.
Anyone with experience on this?
At this point I'm interested in looking at digipots.
Ps, It's 12v and it will be powered in vehicle by 12v auto battery. (will use all 13.5v at 70ml output, but rarely run that high)
No, you actually need a gear reduction between the motor and the pump.
Note: A pump with a stepper motor may be a better choice.
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Is this for medical use?
Your pump is too big.
Hi,
What controller are you using?
Can you please post a link to specs/data of the pump and motor?
What is your overall project?
Tom.. 
Thanks so much Paul, Gil, JCA, and George.
You guys are exactly right. This pump is too big.
However I was off track at 20khz. At .75a
100hz is a good area.
I could get it to run it at 7% duty, but still not slow enough.
It's pumping gasoline on an experimental carburetor, controlled by MAF and Arduino.
Thanks...again!
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