Please Help!!!! L297&l298n

[ruby81]

Hi. I am very very new at stepper motors.
I am trying to build a robot but i can't figure out how to control the motors.
I have plenty of stepper motors from printers.
I tried to build L297 with L298n but i failed...
I have some questions:
My stepper motor is 27 volts , 6.4 Ohm ; so what Vref i need?
Where do i need to wire control , reset ,home, etc...
Thanks.

 

[4pyros]

Did you look at the data sheet?

 

[Angry Badger]

Hi,

When the voltage across the sense resistor (0.5R) equals the ref voltage the L297 will start limiting the current through the L298. So, with Vref equal to 2V, when 4A flows through the sense resistor 2V will be developed across it and the current will be limited.

I think your motor is a little on the large side for an L298. Max current for the L298 is 4A and your motor is rated at 4.2A. At 4A you will notice two things; the L298 will get VERY hot so you will require a very large heatsink and also there will be a big volt drop across the L298's internal transistors so the actual voltage applied to the stepper will be lower than 27V (this would limit the current quite a bit though as well). If you need to actually apply 27V to the stepper the supply voltage to the L298 will have to be much higher, especially at elevated current levels. Try getting a smaller stepper to start with, say 5V or even 12V and a current rating of, say, 1A per phase max. Just use this to learn how the L297 / L298 combination works.

I have a little experience with the L297 /L298 **broken link removed** but am not an expert.

Hope the above post is clear but I'm tired after a long day and am just going to bed. Good luck, steppers can be fun to play with!