Controlling 2 stepper motors with PIC16F84A and 74LS244

[asmie]

Re: two stepper motors

Hi,
Check carefully again, are n't the collectors of each pair of transistors in your original circuit shorted? In that case, your circuit should be OK.

Regards,
Laktronics

to controll two motor not symultinously.when one rotates the other stops,and then and then

---------- Post added at 10:32 ---------- Previous post was at 10:28 ----------

yea,try it to send me!!1

 

[poorchava]

I'd recommend following setup:
-instead of connecting common lead of coils to VCC make 2 current sources out of LM317T and a 2W resistor of appropriate value (see datasheet). Mount those on a heatsink and deliver whatever voltage in 10-40V range.
-for switching coils I'm using TIP122 with base drive resistor of 1k.
-add some fast diode (preferably schottky) across transistor C-E cathode towards collector and anode to GND.
-add same diodes across each motor coil, also cathode towards power supply (or rather current source) and anode to transistor collector
-drive whole thing from whatever Microcontroller you see fit

Maximum current (and therefore torque) depends only on how much power you can dissipate from LM317T. In my experiment I powered whole thing from 15.8V, set current sources to 0.56A. At coil resistance of about 0.9R heatsink becomes HOT.

This is how it looks in reality:
https://imageshack.us/clip/my-videos/269/ljmm.mp4/

btw. pic16f84 sucks in terms or operation speed. of course it's possible to simultaneously drive many motors, but speed won't be that great. I'm actually using 18f2550 (had that at hand). I believe i could drive two more motors at the same speed, controlled individually.