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Decreasing current without decreasing a lot of voltage

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Newbie level 6
May 17, 2015
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My plan is with arduino to power a motor . The motor works fine with 5Volts of Arduino and 200mA but i want to decrease the current in order to rotate slower.
I tried with a digital pin ( 5V , 50 mA) but the motor was not moving . For that i want to decrease the 200 mA to something smaller.

Thank you

If you have variable power supply you connect your motor to 5V and lower the voltage to see how motor behaves. If it rotates slower you will know needed voltage. But this voltage can be too low for motor to start rotating. Without experiment you can not guess what to do.

greetings Borber!
If you read my title i dont want to decrease the voltage but before i posted on the forum i tried to supply the motor with 4.5V and 200 mA and the motor was not moving .I just want to decrease the current for example from 200mA to 100mA and see if the speed of the motor it behaves as i want .

Thank you

I am afraid in this case you can do nothing. You have wrong motor.

First try (without arduino) to supply 12v through a variable resistor and a 5v1 zener or diode voltage regulator in parallel with your motor if you must control using current. If it works out you are good to go. Alternatively ignore the zener or regulator and just vary the voltage if the motor can handle your supply. If it works you are good to go. if neither of the above works, do as Borber says. If it works however, now design an electronic circuit with transistors or what you are in possession of to raise the arduino output voltage to the value of the supply you tested with.

You could experiment by first raising the arduino output voltage using transistors to a higher voltage by supplying with a higher voltage say 12v. Then you could use a variable resistor feeding a 5v1 zener diode in parallel with your motor.


if you want to decrease current, but with same voltage and same motor you have to decrease torque. I can´t see another way.

A motor with a voltage control loop behaves more like a revolution control. So changing voltage is the way to go if you want to lower speed.

A motor with a current control loop behaves more like a torque control. With no torque it has high speed and with higher torque speed decreases.

A vaery usual way is to use a PWM control for the motor. Then you should start with full duty cycle to start the motor, and once it runs you could lower duty cycle und thus lowering speed (and current).


A motor will take whatever current it needs based upon the load, motor speed, and voltage.
You can't reduce the current without reducing the voltage.

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