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dc to dc power converter

Discussion in 'General Electronics Discussion' started by din noh, Apr 28, 2010.

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  1. din noh

    din noh

    Apr 28, 2010
    can this circuit drive a 24Vdc servomotor?
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    probably not.

    The gates will be the first issue (aside from the 12V battery). You need to be able to drive the gates appropriately.
  3. 55pilot


    Feb 23, 2010
    I am not sure if that circuit will reliably drive a 12V motor either. If both the forward and reverse signals are high at the same time, you will have all 4 MOSFETs on, followed by smoke and sparks.

    I am not sure what the analog circuit is doing or trying to do.

    Finally, this is not a DC-DC power converter.

  4. NickS


    Apr 6, 2010
    Hello din noh,

    I am not familiar with part abreviation 324 is it a comparator or an op amp? I will assume a comparator which would be appropriate for what the upper right portion is trying to do(oscillator right?)

    However below that you have a 741 op amp with +/- 12V rails driving a 0-12V comparator used as a buffer which is bad. You have the potential of placing an input voltage on the 324 buffer that is significantly lower than the lower rail voltage which could bring smoke and latch-up, not to mention it is just bad foresight even if it does not fail.

    moving on I am presuming that you are using the input to the 741 as a choke switch for the oscillator, but I don't think it will work quite as you want.

    Finally are you sure your logic devices have the ability to drive the FET gates all the way on? If that is anything short of 15v logic then your logic will see higher potentials on the outputs then their VCC which would again be potentially bad. Also the lower FETs could be operating in a higher on resistance state that makes heat and ruins parts at high current

    And to mirror 55p this is not a DC-DC power converter it does however resemble an
  5. din noh

    din noh

    Apr 28, 2010
    thanks a lot u guys, i appreciate your concern regarding on your effort..
    what is suitable driver for DC servomotor?
  6. alertlink


    Apr 29, 2010
    This is a 12V dc motor speed control cicuit with forward and reverse function(cw and ccw). Not complete though. It functin like this , upper two 324 operational amplifiers make a triangle wave generator. Lower left 1/4 lm324 compares triagle wave with input set point and hence outputs pulse train with variabe duty cycle. Gates drive full hbridge circuit which in turn drive dc motor. Gates also povide polarity reversing function. 741 circuit can drive in -Ve region can be omitted applyyin control voltage directly to324 input.For 24V gates drive cen be replaced with some transistor driver stage.
    Last edited: Apr 29, 2010
  7. din noh

    din noh

    Apr 28, 2010
    I am starting to understand the function and flow of this circuit. In order to implement this circuit for 24v input, can you list down all the change needed? I appreciate if you provide links where there is explanation about my problem especially on this particular circuit.

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