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PWM Circuit

Discussion in 'General Electronics Discussion' started by Edwin Fitzpatrick, Jan 18, 2013.

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  1. Edwin Fitzpatrick

    Edwin Fitzpatrick

    23
    0
    Dec 26, 2012
    I built a PWM motor control circuit using a TL494CN chip, Workes good ,But can not go to 100% on . How do I get this chip to go from off to full on. IT will go full off but will only go to 95% on at full pot.The circuit is from Electronica,60 A PWM motor controller Article.
    Tnx,Fitz
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    The TL494 has bipolar switching elements. Depending on your topology, there may be a voltage drop that you can't easily avoid.

    Post a link to the schematic.

    A simple solution may be to start with a slightly higher input voltage to compensate for the losses across the switching elements.

    edit: Is it this?
     
  3. Edwin Fitzpatrick

    Edwin Fitzpatrick

    23
    0
    Dec 26, 2012
    Hi Steve,
    The Web site is in my message ,ELECTRONICA,60 A PWM MOTIOR CONTROLLER.This is a circuit for a electric scooter,What I am building is a 36 volt electric cart.I need 100% on when I push the throttle to the floor.IT uses 10 IRFZ48 Hex ferts in Parallel.The article says that the circuit will go from 0 to 100% pwm.I tried all modification to the circuit and the max I can get is 95 %. IT goes to 0 % ok. This may be the best the TL494CN will do.Why would anyone want to build a motor controler that would not go to 100% on ?????
    Fitz
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    The TL494 has bipolar switching elements. Depending on your topology, there may be a voltage drop that you can't easily avoid.

    Post a link to the schematic.

    A simple solution may be to start with a slightly higher input voltage to compensate for the losses across the switching elements.

    Is it this?

    edit: Not that I want to repeat myself, but you have not addressed any of these vital issues. And there is no link in either of your posts.
     
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