DC motor power supply info needed

bill stupak

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I want to use this motor to power this grinder. It has the proper hp and rpm for the grinder. The motor is 90v DC, .25 hp, 2.6a. I’m looking to find out what kind of power supply or controller I should use? I had the motor powered up with a KBIC 125 controller from another project and was looking at getting another, when I saw these on the website


Would any of these be appropriate for this application, Full disclosure, my working knowledge of electronics is pretty limited, I don’t need variable speed and would like to keep it as simple as possible, as close to plug and play as possible.

IMG_0016lienhard.jpgmotor.jpg
 
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An a/c fan control, a bridge rectifier, and the right pot is all That is needed to power a d/c motor. I spent less than $30 to build one. Google Mike man made to see how I did it (I copied him).
 
Thanks, that looks very doable for me. One question, Mike never said what size pot he ended up using, what size did you use? I know the one I have on my mini mill is 5k. Stu
 
He didn't because it can be different with every d/c motor with different specs. The motor that I was using is 3.2 hp, 200 and change volt d/c.

I got a kit off of Amazon with 10 different pots and changed them out until I found the right one. You will know it when you find the right one. It was dirt cheap. I can post a picture later tonight if you are interested.
 
Hi Bill- Harbor Freight sells a router control which you could use in conjunction with a bridge rectifier (Ebay)
That would only set you back about 30$
You could substitute an ordinary light dimmer for the router control and save even more
-mark
 
Example diagram: (if using light dimmer, connect in series with hot line wire. Neutral connects directly to bridge)
routercon.jpeg
 
The KB controllers have better speed regulation under load, but of course they cost more
 
Don't forget the ground wire! A nice green ~14 gauge or so from the motor frame to the dimmer chassis to the AC plug's ground pin. You never know when an old used motor (or cheapy dimmer) will short to its case and maybe zap you.

[Edit] As Bill mentions below, the ground wire should match the wire gauge of the line cord which must be sized for the current draw and to some extent the breaker size feeding the outlet. In this case, I was assuming your line cord will be somewhere around 16 or 14 AWG on a 15A circuit.
 
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AMEN to the ground wire. It should be as large or larger than the line cord. And long enough to be the last pulled loose if the cord is yanked out. Of course, I predate OSHA by a few years. From the days when a true electrician would stick his finger in a lamp socket to see if it was live. That was a long time ago.

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