can any one help plz enter

I have a question I hope someone can help me
I am currently building my CNC machine and I have actually started getting to the point of building The Driver I find a good driver in this site www.ifrance.com/mac1 and i build it for unipolar motor's i have 3 motor's 4.0v and 1.6A and i use power supply 6A and 24V and in the circuit say to put a resistor 5w .5ohm , can any one tell me how can i run the motor in the best mode how many voltage can i use and what about the resistor when i change it to 5w 5ohm the motor did't run and i cann't uderstand why

plz help me to run the motor in the best mode and what resistor i use to achive the max oz

thankes

Ahmed, the .5 ohm resistor is used to control the current to your motors. Your motors won't run because 5 ohms will give you only 200ma of current (if I'm not mistaken). You need to look in the L297 data sheets to see what value you need for 1.6 amps. I think it has to be .62 ohms.

The voltage does not matter much, since the controller will do the current limiting. Generally the higher the better, but don't exceed the rating of chips.

I think you might have trouble with resonance because the circuit does not have microstepping. If you want to get full performance out of your motors, you should use a different circuit. Check out Phil's a3977 board in the open source forum.

thanks , but this chip i cann't find in egypt

L298 , L297 only can be find here

plz H500 tell me how to colect ohm for motors amp

ahmed,
Here is a link to what we have done in the open source forum for the L297-8:
http://pminmo.com/l297-8/l297-8.htm

My website:
http://pminmo.com
This board would work with your motor. The board you referenced is using a discrete approach for higher currents than you need.

Phil