circuit mods for briving a bipolar/hybrid stepper

[m3vuv]

hi all ive a schematic for driving a unipolar stepper,can it be made to run a bipolar?

[m3vuv]

Well it seems like a waste of time asking here!!

[langwadt]

Well it seems like a waste of time asking here!!

I'm sure you can get a full refund ....

[mikerj]

The answer is no.  To drive a bipolar stepper you need an H bridge for each winding.

[m3vuv]

This is the code im using:

/*

http://www.bristolwatch.com/radio/arduino_coil_winder.htm
Arduino Stepper Motor Coil Winder
Lewis Loflin
lewis@bvu.net

*/



#define yellow 9  //Q1
#define orange 10  //Q2
#define brown 11  // Q3
#define black 12 // Q4

#define SW0 2
#define SW1 3
#define SW2 4
#define SW3 5

#include <OneWire.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
// set the LCD address to 0x27

int i, j;

void setup()  {

  pinMode(SW0, INPUT);
  pinMode(SW1, INPUT);
  pinMode(SW2, INPUT);
  pinMode(SW3, INPUT);

  digitalWrite(SW0, 1); // pull up on
  digitalWrite(SW1, 1); // pull up on
  digitalWrite(SW2, 1);
  digitalWrite(SW3, 1);

  lcd.init(); // initialize the lcd
  lcd.backlight();

  pinMode(black, OUTPUT);
  pinMode(brown, OUTPUT);
  pinMode(orange, OUTPUT);
  pinMode(yellow, OUTPUT);
  all_coils_off();

  lcd.clear();
  lcd.home();
  lcd.print("Wait 2 sec.");

  delay(2000); // wait for 2 seconds
  lcd.setCursor(0, 1); // is Home
  lcd.print("Ready to go!");

  j = 0;

}

void loop() {

  // set turns
  if (!digitalRead(SW0) == 1)   {
    delay(1000);
    j = 0;
    lcd.clear();
    lcd.home();
    lcd.print("Turns = 0  ");
    while (!digitalRead(SW0) == 1)   {
      delay(1000);
      if (!digitalRead(SW1) == 1) j = j + 1;
      if (!digitalRead(SW2) == 1) j = j + 10;
      lcd.setCursor(8, 0);
      lcd.print(j);
    } // end while
    lcd.setCursor(0, 1);
    lcd.print("Ready to wind.");
  }

  if (!digitalRead(SW3))  {
    lcd.clear();
    lcd.home();
    lcd.print("Turns 0  ");
    for (i = 1; i <= j; i++)   {
      reverse(200);
      lcd.setCursor(6, 0);
      lcd.print(i);
    }
    all_coils_off();
    lcd.setCursor(0, 1);
    lcd.print("Finished ");
  }

} // end loop


void all_coils_off(void)  {
  digitalWrite(black, 0);
  digitalWrite(brown, 0);
  digitalWrite(orange, 0);
  digitalWrite(yellow, 0);

}

void reverse(int i) {
  while (1)   {
    digitalWrite(black, 1);
    digitalWrite(brown, 0);
    digitalWrite(orange, 0);
    digitalWrite(yellow, 1);
    delay(analogRead(0) / 4 + 5);
    i--;
    if (i < 1) break;

    digitalWrite(black, 0);
    digitalWrite(brown, 1);
    digitalWrite(orange, 0);
    digitalWrite(yellow, 1);
    delay(analogRead(0) / 4 + 5);
    i--;
    if (i < 1) break;

    digitalWrite(black, 0);
    digitalWrite(brown, 1);
    digitalWrite(orange, 1);
    digitalWrite(yellow, 0);
    delay(analogRead(0) / 4 + 5);
    i--;
    if (i < 1) break;

    digitalWrite(black, 1);
    digitalWrite(brown, 0);
    digitalWrite(orange, 1);
    digitalWrite(yellow, 0);
    delay(analogRead(0) / 4 + 5);
    i--;
    if (i < 1) break;
  }
}
can this be altered to include the stepper librarys and use a polulu driver for a bipolar stepper,it seems to work spot on to my needs except i cant run my bipolar motor with it,any one want to show me how to do this?

[m3vuv]

ive heard a bipolar hybrid can be run as unipolar?,anyone expand on this?

[JacobPilsen]

How many wires have your motor ?

[m3vuv]

Hi,the motor has 6 wires,i need to try and run it with mosfets and the sketch i posted.

[Someone]

https://lmgtfy.com/?q=stepper+motor+6+wire+unipolar&s=g

[m3vuv]

Thats great,the issue is,the chematic is for an 8 wire unipolar,i only have 6 wire hybyds,thats the whole point of my post,i need  to know how to connect mine  to the circuit in the schematic,if its at all posible.

[george4657]

You have a 6 wire unipolar motor that has two center tapped coils. You would feed power to the 2 center wires of each coil. One wire to the center tap becomes L1 and the other wire to center tap becomes L2 in your drawing. The same for the other coil one end  to center tap is L3 and the other end to center tap is L4.
Google  "6 wire stepper driver" and you will find 6 wire motors wired as per your drawing.

The problem with such a simple driver is there is no current limiting. When a Fet is turned on the current through the coil will be restricted only by the resistance of the coil. Measure the resistance of 1/2 coil ( end to center tap). Divide voltage by this resistance and you will get the current flowing through the coil. If current is
greater than rating of your motor it will burn up the motor.
There will be two and only two coils driven on each step so total current is doubled. 

[m3vuv]

no george i dont have a unipolar motor,i have a 6 wire bipolar hybryd.

[m3vuv]

heres the datasheet for my motor attached.

[martinayotte]

This PDF is clearly shows a unipolar stepper where white/yellow are center taps.

[george4657]

If you had shown the motor datasheet you would not have wasted so much time. Your driver is designed for a small toy motor driven with an arduino. You have a hybrid nema 23 motor that requires a proper driver to run it.
If you tie the center taps together you have a unipolar motor, if you cap off the center taps you have a 4 wire bipolar motor, this is why it is called a hybrid.
Hooking your driver up to this motor would blow the Fets and/or the coils of the motor.
A cheap 3d printer bipolar driver would work but you would not get the full power of the motor.

We could better advise if you explained what you are going to do with the motor.

[m3vuv]

Hi,its to build this.http://www.bristolwatch.com/radio/arduino_coil_winder.htm

[m3vuv]

it looks like my motor can be run as a unipolar,i just need how to go from 8 wires as per the sort of schematic i posted from 8 wires to 6,i dont want to alter the code unless i have to as the control part of things work fine,ive altered the code to use another button,so button 1 is set,button 2 is ones of turns button 3 is tens and ive added another for hundreds of turns,set the turns press go and off it goes flashing the leds and counting down.

[martinayotte]

i just need how to go from 8 wires as per the sort of schematic i posted from 8 wires to 6

Yellow and White wires are common wires for 2, let says L1/L2 on on Yellow and L3/L4 on White.
Since your driver has all coils to V+, simply put Yellow/White wires to V+, the rest of the schematic is identical, providing GND using MOSFET to the GND side of the coils ...

[george4657]

Unless you are powering the motor with a 3 volt supply you would also need current limiting resistors between each centertap and power supply.
If using 5 volt supply you would need at least 1.0 ohm resistors. ( 1 ohm at 2 amps = 2 volt drop)