PWM Help needed

[Roland Jacques]

I'm looking at making a different Water Vapor Injection system. So i wanted to know if a PWM would work with this 12 volt Air pump? (adjusting air pump output)
http://www.castnetworld.com/airpumps.html
I cant find more details on this pump, or even the manufactures name, but it looks like a a simple rotary motor attached to a diaphragm pump. Any help appreciated

[H2OPWR]

I'm looking at making a different Water Vapor Injection system. So i wanted to know if a PWM would work with this 12 volt Air pump? (adjusting air pump output)
http://www.castnetworld.com/airpumps.html
I cant find more details on this pump, or even the manufactures name, but it looks like a a simple rotary motor attached to a diaphragm pump. Any help appreciated

Roland, My water pump is a little different than yours but I have run both it and a vacuum pump with a PWM many times. They both worked very well. After all a PWM is simply a vairable speed DC motor speed control. I think it would work great.

Larry

[Philldpapill]

You should probably use a fairly low frequency for the PWM. The water pump looks like a big inductor, and if you use a REALLY high frequency(>1kHz), you may not get full power. In addition, you will need an extra diode in anti-parallel with the pump. This is to absorb the back EMF produced when the PWM turns off.

[Roland Jacques]

Thanks guys