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controlling speed of dc motor Answered

Hey guys I'm trying to finish a project.  I have a motor thats making a 5 gal bucket spin, I would REALLY like to be able to control the speed but I'm not sure how to go about it.  Right now it's spinning extremly fast and to unstable

The motor I used is decently small

I've read similar problems and ppl suggest PWM what size do I need for the motor I have?



Best Answer 8 years ago

This tutorial explains how to vary the speed of a motor using PWM.

You asked "what size do I need", the 555 timer IC can use the same 12V supply you're using for your motor, the 555 will draw the current it needs, the mosfet in the diagram I linked to will allow the motor to draw the current it needs without drawing it through the IC, the IC will just control when current can flow through the mosfet and hence the motor.

If you don't want to build your own PWM controller you could buy and use something like this: http://cgi.ebay.co.uk/12V-15A-DC-Motor-Speed-Control-PWM-HHO-RC-Controller_W0QQitemZ320484177668QQcmdZViewItemQQptZUK_BOI_Industrial_Automation_Control_ET?hash=item4a9e587704

Hmmm my previous comment wont let me reply to it....

I meant to hyperlink that insanely long url. Linky

Jayefuu, something is wrong with your word wrap today.  Part of your comment is hiding under the related col.

Testing why it won't let me reply...


Using a POT is a very bad idea. The motor regulation - its ability to stay running under a load is badly compromised. The better way is to use a variable voltage regulator, like an LM 317


I don't know how this might affect everything else, but basically put a variable resistor (potentiometer) in series with the motor. This should allow you to control the amount of electricity going to the motor. If it's a fancy motor perhaps there is a better way of doing things, but for a normal simple DC motor I believe this is the standard (or at least easy) way of doing things.

That's a good idea. I was going to suggest useing a remote controlled ESC but you idea is way cheaper.