treadmill speed control help

Discussion in 'The Projects Forum' started by majorkuso, Oct 23, 2015.

  1. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    We have a treadmill, but the motor control and psu unit died(one unit).What I am trying to do is control the speed of the motor with preferably a 555 timer. the motor is a DC 2hp 90v rated at 20 amps. i have a few power mosfets one rated at 100v at 100 amps. We have a fwb rectifier that drops the unregulated voltage down to about 90. i think I am overthinking the driving of the motor. i thought about putting a zener regulator to supply the power to the timer circuit but am not sure about driving the mosfet and motor.
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745
    Are you thinking of using a 555 in pwm mode to drive the mosfet, running the motor direct from the mains via a bridge rectifier?
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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  4. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    in short yes, but running the motor from mains through the bridge could cause problems I think.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It is done all the time with T.M.'s and KB DC motor controllers.
    Max.
     
  6. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    the speed controller that was bought to run it could handle the rated current. i am trying to create a custom solution.
     
  7. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    wouldn't a steadier supply other than a fwb give better control
     
  8. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    the fwb drops the voltage anyway so that is not the problem.
     
  9. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    I may have a 200 v powerfet will look when I get home.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Sorry, what is fwb?o_O
    Max.
     
  11. majorkuso

    Thread Starter Active Member

    Aug 21, 2009
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    Fill wave bridge sorry for not clarifying earlier
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Surely the voltage drop of a bridge is rather trivial at 120v.
    Max.
     
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