problem with stepper drivers uln2803

[thinkbig]

I am using two stepper motors for my micromouse..
To drive two steppers can i use only 1 uln2803..

please help me understand the difference between the two circuits above..

my stepper specification is 500mA,6-12V..

so for my specification which of the above two circuits is better??

How to select the value of zeners to be used for my stepper specification??

please help..

 

[blueroomelectronics]

Why are you using Zeners? Just tie the clamp (pin10) to +24

 

[Ubergeek63]

Neither!

You can NOT run your 12V stepper from 24V!

You can NOT connect the clamp diode! ( the two windings are on the same iron, and you will be shorting out the windings since each winding pair acts like an auto transformer )

Your switches need to be able to have more than double the breakdown voltage of the supply.

Dan

 

[blueroomelectronics]

Ahh I missed the 12v stepper on a 24v supply. Although it's common practice to run steppers at higher than rated voltage if you're careful.