View Full Version : Using TIP142 insteed of TIP120 to run stepper motor.

10-09-2010, 07:17 PM
I am going to use TIP142 in steed of TIP120 in the following picture and want to operate the stepper at 24V. so which resistor I should use? Or what is the rule of thumb to use resistor.

10-09-2010, 07:39 PM
I already gave you the equations in the attachments on the previous thread (http://www.mycncuk.com/forums/showthread.php/2039-Unipolar-stepper-motor-with-ULN2003?p=13913&viewfull=1#post13913). The TIP142 wont change what resistor you use and you will still have the same heatsink problems as the TIP120. GO back and re-read that thread, then post your own calculations and I'll validate them for you....