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Thread: :? Comparison of steppers...and overdrive doubt :?

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  1. #1
    Senior Member Android
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    Default :? Comparison of steppers...and overdrive doubt :?

    I now have finally got 2 pair of steppers of given ratings clearly written:
    SM1:
    6v 1A 1.8deg steps
    SM2:
    12v 0.3A 1.8deg steps

    well after a lot of assessment i can't decide which one of the will give me better result for a micromouse.
    After going through site's forums,googling all the day..i still have some firm doubts,pls clear them:
    My Opinion:
    1.12v will give me less torque but would not at least burn my uln2803/uln2003??
    2.can I safely overdrive SM1 till 15V using uln 2003 (only)??? or should i use 10ohm 1W resistors for chopping??(NO COSTLY IC INTENDED)
    3.6v is better as more current and less voltage,but would surely burn my uln,so i would over drive it at 9v with 10ohm 1w resistor...(correct or not)
    what should i do.which one should i use??

    4.is there any driver with l298 alone driving unipolar stepper???(not with l297) :roll:
    5.will chopping 6v with resistors save my uln?? but will it give me enough torque?? :? :?

    The best way is if any one please provide me link to pt3.I can afford only l298 not l297 for i m an online buyer and ots not available(have checked regular vendors)

  2. #2
    Senior Member Android
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    is it true that i can replace l297 in l297+l298 motor driver(in datasheet) by my muc (MEGA32) ??
    can it safely drive and overdrive my steppers??

    "The 5 volt 1 amp motors are driven by 9 volt supply. I had used 15 ohm resistances to limit the current and 3.3 k resistances for pullup in the base. 1N4148 are used as protection diodes."
    http://www.roboticsindia.com/modules...ewtopic&t=1358 the link from where it was taken

    what is this"3.3 k resistances for pullup in base" :?

  3. #3
    Senior Member Android
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    which one of the will give me better result for a micromouse.
    u already have the answer. if you need more torque use 6v 1A. else go for 12v...... i am also currently working on micromouse. i have got 12v unipolar stepper. its fine if your final robo wiegh less than 1kg. i have to do serious changes for the dieting of my mouse as no other type of stepper is available here..... so just estimate the weight (including battery).....

    overdrive SM1 till 15V using uln 2003 (only)???
    no. it will burn your ic

    should i use 10ohm 1W resistors for chopping??(NO COSTLY IC INTENDED)
    overdrive using resistor is only waste of energy. it is only useful if you have no low voltage source available. there is no point in choosing a high volt supply and then use half of the voltage only.

    6v is better as more current and less voltage,but would surely burn my uln,so i would over drive it at 9v with 10ohm 1w resistor...
    ya 6v is better..... but 9v with 10ohm +6ohm(stepper)=.56A ........ you are getting half torque only with incresed burden of batteries. better than this is to use 5v or 6v with 6ohm resistance......

    if you dont want to use l297/l298 you can use transistors with high ratings... they can withstand high current but will consume more pcb space...... also remember its not always necessary to overdrive

    what is this"3.3 k resistances for pullup in base"
    serch for pull-up and pull-down resistors..... we often use them with microcontrollers..... in my words i can explain them as- they are used to convert a tri-state situation( high,low, high impedence) to 2-state situation (high and low)...... its like replacing high impedence state with either 1 or 0........... see link:
    http://www.freewebs.com/maheshwankhede/ports.html

  4. #4
    Senior Member Android
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    hey! i got on stand alone l298 stepper driver:
    http://www.pyroelectro.com/tutorials.../schematic.gif

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