speed of dc motor

Discussion in 'The Projects Forum' started by slimnick, Nov 28, 2007.

  1. slimnick

    Thread Starter Member

    Nov 25, 2007
    21
    0
    i am wondering it there is anyway to slow a small dc motor the can be bought to slow its RPM to only make 2 revolutions per second.
    input voltage = 12Vdc.

    i dont know if its feasible but just thought i would ask.
    thanks for your help:cool:
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    What is the unmodified motor speed? And what kind of torque do you need?
     
  3. Voltboy

    Active Member

    Jan 10, 2007
    197
    0
    If you calculate the speed then you could use gears or even PWM, but it would be kinda hard to determine the right values.
    I think it would be easier using a modified servo or a stepper motor.
     
  4. eeboy

    Active Member

    Sep 27, 2007
    90
    1
    I tend to agree with Yoda. If you don't need a large torque then a stepper motor would be the easiest method to achieve exactly 2 RPM.

    If the rated RPM is on the lower end (say 100 RPM or lower) then you may be able to achieve reasonable (good enough) results by trial and error with PWM (or a similar method to control the current).

    Otherwise you are probably going to need to develop a full blown control system.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    2 RPS is 120 RPM - should be no problem with PWM drive. It might be easier to find a gearhead motor that delivers about that output without needing a speed control. You get torque multiplication as an added benefit.
     
  6. Voltboy

    Active Member

    Jan 10, 2007
    197
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    but he wants 2 RPM not 2 RPS
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    I still read 2 rev/sec.
     
  8. Voltboy

    Active Member

    Jan 10, 2007
    197
    0
    oops.. sorry i only did saw the RPM and stop reading :p
     
  9. slimnick

    Thread Starter Member

    Nov 25, 2007
    21
    0
    ok i found a schematic for a PWM ill give it a look over and if any problems ill write again. thanx:D
     
  10. Voltboy

    Active Member

    Jan 10, 2007
    197
    0
    It will be kinda hard to get 2 RPS with PWM.
    Why do you need it at exactly 2 RPS?
     
  11. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That's why I suggested a geared-down motor. Much easier to use PWM successfully.
     
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