Voltage controlled coil driver

Discussion in 'The Projects Forum' started by ocelot28374, Apr 17, 2012.

  1. ocelot28374

    Thread Starter Member

    Apr 16, 2012
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    Here is a block diagram of what I am looking to build. if someone could help me fill in the circuits.

    Thanks
     
  2. chrisw1990

    Active Member

    Oct 22, 2011
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    sorry but can you elaborate? i got more from your title i think than the image..
    in brief:
    you want an analogue voltage to control your coil?
    from 0- ~30V?
    have you got an intended application? and therefore photos etc?
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Sort of sounds like you want a constant current source where you can set the current level with an analog voltage? (Like a typical LED driver where you set the output current with a 0-10V PWM or DC signal)

    What exactly are you trying to power and how? Try simple laymans terms..
    What is this mysterious "electromagmetic" coil? A speaker coil? A solenoid? Got a part number?
     
  4. ocelot28374

    Thread Starter Member

    Apr 16, 2012
    31
    0
    It is for a braking device. The coil is an electromagnetic coil from a trailer brake. Repurposed to slow a rotor based on a specific voltage condition. Any voltage in excess of 27 volts starts to apply current to the magnetic coil proportional to the over voltage condition.
     
  5. wayneh

    Expert

    Sep 9, 2010
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    Ah yes, your windmill brake. Do you have specs for the trailer brake and its coil?
     
  6. ocelot28374

    Thread Starter Member

    Apr 16, 2012
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    They can typically handle about 10 amps current individually. I had in visioned using two in parallel. The physical brake, I am redesigning completely. It would be to heavy and apply to much force from factory design.

    I do appreciate your help. I am attempting to be as direct in concept as I can.
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,100
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    OK good, that means you need a control system capable of delivering smooth variable control in the range of 0-20A (I assume at 12v?). Do you have any details on how these brakes are normally controlled? I mean, automotive brakes are normally hydraulic and the pressure applied at the wheel is proportional to pressure applied by the driver at the pedal.
     
  8. ocelot28374

    Thread Starter Member

    Apr 16, 2012
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    The coils of the brakes are normally controlled using a brake controller that is enabled thru the brake light switch. The force of application is controlled by selecting the desired"feel" from the trailer. The controller uses a set voltage controlling current delivery. This can be a pulsed signal at some specific frequency or steady energy. The pulsed method has the advantage of using less power and smoother braking action (cycling the magnet on and off quickly allows less "grab") 24 volts is the system voltage, I would like to take advantage of that to reduce complexity.
     
    Last edited: Apr 17, 2012
  9. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    Ever drive a big rig down a mountain grade? If we're talking about friction braking you better add a "Minimum Smoke" pot to your system. :D
     
  10. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,036
    This is more like a pinwheel or beanie copter. A trailer brake should be massive overkill.
     
  11. ocelot28374

    Thread Starter Member

    Apr 16, 2012
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    0
    :) probably, the plan is not to allow the coils to come into contact with the rotor, rollars spring mounted to provide force against the rotation of the rotor. it does weight about 20 pounds. rotating in high winds its alot to try and slow down.
     
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