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Amplifying PWM signal

Discussion in 'General Electronics Discussion' started by willingtolearn, May 3, 2014.

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  1. willingtolearn

    willingtolearn

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    May 3, 2014
    Hi guys!

    I'm new to the forum and a novice at electronics but not totally clueless. My question is this;

    I need to take a PWM signal from a printers carriage motor, amplify it, and feed the same control signal to a larger motor with more power. I'll need to be able to adjust the amount of power via a POT. Any help is appreciated and I look forward to becoming less of a newb. :p


    Ryan
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    PWM already controls the amount of power. So there's no reason for a pot because you'd be changing the PWM signal.

    A lot depends on the type of motor. In the simple case you just use the existing PWM signal to switch a suitable mosfet (or a suitable power bipolar transistor).

    If it's a stepper motor or a brushless motor then the signal is not PWM, or there's more going on than just PWM and the problem becomes potentially more difficult.
     
  3. willingtolearn

    willingtolearn

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    May 3, 2014
    Thanks for the response! I'll give a little more info that might clear things up. The motor is basically a brushed DC motor. When the printer's logic sees that the duty cycle gets too high on the motor, it causes it to slow down and pause at the end of each pass.

    What i need to do is keep the duty cycle low, so the printer thinks everything is fine and it's not overworking itself. I've tried a larger motor with no success. Any suggestions?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    That would require a change in the logic in the printer's software. It would be difficult to prevent the motor slowing down (but would possibly be doable), but it would be a whole other kettle of fish to remove the time delay.
     
  5. willingtolearn

    willingtolearn

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    May 3, 2014
    maybe i should say my goal isn't to completely remove the slow-down, but to beef it up to the point where it can overcome friction built up on the print shaft. maybe a 20 or 30% gain
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    OK, so what are the specs on the original motor and on the new one?
     
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