# Make hard drive stepper motor run 7200 rpm

I have an old hard drive (7200 rpm) motor like this:

I'm trying to make it run as fast as possible and I start with this code (arduino uno):

int pin1 = 2;
int pin2 = 3;
int pin3 = 4;

int delay_time = 100;

void setup() {
pinMode(pin1, OUTPUT);
pinMode(pin2, OUTPUT);
pinMode(pin3, OUTPUT);
}

void loop() {
digitalWrite(pin1, HIGH);
digitalWrite(pin2, LOW);
digitalWrite(pin3, LOW);
delay(delay_time);

digitalWrite(pin1, LOW);
digitalWrite(pin2, HIGH);
digitalWrite(pin3, LOW);
delay(delay_time);

digitalWrite(pin1, LOW);
digitalWrite(pin2, LOW);
digitalWrite(pin3, HIGH);
delay(delay_time);
}


The motor runs when delay_time bigger than 50 (it run very slowly of course), with delay_time smaller it just "vibrate". So how can I make that runs at 7200 rpm?

UPDATE:

I use other source and some transistors for motor, not use arduino pins.

• Microcontroller pins are not meant to drive motors, you need a driver device. You may also need a higher voltage depending on winding inductance. Are you sure that is actually a stepper, and not a BLDC motor intended for 3 phase sinusoudal drive between the windings? Jan 22 '15 at 4:01
• @ChrisStratton: I use other source and some transistors for motor, not arduino pins :( Jan 22 '15 at 4:09
• @ChrisStratton: I think a BLDC motor should has 3 wires out, but here has 4. Jan 22 '15 at 4:25
• Watch this video. I think it is in Dutch, but there are english subtitles available (You have to enable them). youtube.com/watch?v=CMz2DYpos8w Jan 22 '15 at 4:49
• Running HDD Motor using Sound Card of the PC youtu.be/R9Q1XrFZr5E
– user115627
Jul 2 '16 at 8:22