Controlling 2 stepper motors with PIC16F84A and 74LS244

Re: two stepper motors

laktronics said:

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

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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

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.