Use 12V voltage regulator and a variable 0 to 30V DC power supply to control the 12V DC motor speed

dc motorspeedvoltage-regulator

I've got a 12V DC motor with:

  • Output power: 3.4 watts
  • Rated speed : 170 RPM
  • Rated current: 0.9A

Currently I have a variable voltage DC power supply which can vary the voltage from the DC power supply from 0 to 30V and an LM7812 voltage regulator.

Can I slow down the motor speed by decreasing the voltage from the DC power supply? I am still unsure what speed is suitable for my motor to rotate in my final year project.

Beside that, there is a lot of things that confuse me and I need some justification.

  1. Some people say if I use the 12V L7912CV voltage regulator in my circuit, the current that passes through the voltage regulator is not high enough to activate my DC motor. This is the link of the data sheet L7912CV.

  2. Some people say if I use a resistor to control my motor speed, the resistor will easily get burned up.

  3. The goal of the DC motor is to rotate a disc which is in direct contact with a flat surface so there is friction between them. So in an ideal case, if I buy a 12V power supply and directly connect to the motor, due to the friction and the load, the rated rotating speed will decrease and is suitable for my project. So in my circuit board do I need to buy any other stuff beside a 12V power supply?

Best Answer

pwm
(source: robotroom.com)

Here is a simple example of how to drive DC motor with Transistor and PWN. The diode is to protect the circuit while the motor is free spinning and to stop fail gating the transistor. The resistor is protection for the pulse generator i.e. micro controller or 555 chip or the many other ways to make PWN signal.

Related Topic