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Variable DC

colum

Jul 25, 2013
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I want to drive a small DC motor with a 12 volt battery
I need to vary the voltage to the motor from about 6v to 9v to speed control
If possible I would like a simple circuit.
An ordinary wall plug in transformer works well but is not variable.
Thanks for all advice
Jeff
 

kellys_eye

Jun 25, 2010
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Motor speed control is usually achieved using a PWM (pulse width modulation) system - varying the DC will work but won't help when the motor is under load. Small motor control modules are readily available and very cheap.


Typical (but not only) example and that price is for THREE!
 

colum

Jul 25, 2013
175
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Messages
175
Motor speed control is usually achieved using a PWM (pulse width modulation) system - varying the DC will work but won't help when the motor is under load. Small motor control modules are readily available and very cheap.


Typical (but not only) example and that price is for THREE!
Thanks kellys eye
They do not mail to the US.

I will try for a 3055 and some variable resistors
Standby for the smoke
 

Kiwi

Jan 28, 2013
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Amazon and Ebay have lots of these PWM speed controllers.
 

Bluejets

Oct 5, 2014
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Probably $2.00 on one of the online suppliers.
Can't buy the bits for that.
 

colum

Jul 25, 2013
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Thanks Minder for your circuit
I built a PWM circuit with 2 555s and a transistor and the results looked great on my meter
that went down to 6v but when I hooked it up it the speed did not seem to vary
I'm sure it was my error.
so I will try for a regular voltage reducer with a 3055 etc
Jeff
 

crutschow

May 7, 2021
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so I will try for a regular voltage reducer with a 3055 etc
Depending upon the motor current the 3055 will require a heat-sink.
That's the advantage of using PWM, as the transistor requires little or no heat-sink.
 

davenn

Moderator
Sep 5, 2009
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Thanks kellys eye
They do not mail to the US.

I will try for a 3055 and some variable resistors
Standby for the smoke

just do a search for the same product on your USA ebay
Small DC Motor 5A PWM Controller Speed Control Driver Board

tisnt difficult
it's the ONLY way you will be able to reliably control the motor
As others have said, your variable voltage scheme wont work properly
as the voltage needs to be kept stable
 
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