Can I replace BJT with AND gate in the following circuit

Discussion in 'The Projects Forum' started by vivek20055, Nov 5, 2012.

  1. vivek20055

    Thread Starter Member

    Nov 4, 2012
    88
    0
    Hello,

    I have to replace transistor with AND gate in my project. How this can be done?. Can anyone suggest me something about this?.




    Thanks & regards,
    Vivek Alaparthi
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,664
    634
    What is the function of the transistors?
    They appear to be some sort of level sensitive switches that produce pulse width modulation or something similar.

    What can you tell us about the circuit?
     
  3. vivek20055

    Thread Starter Member

    Nov 4, 2012
    88
    0
    Hello DickCappels,


    Thank you for your reply,

    This circuit is a external synchronous self oscillator ZVS converter.
    As long as voltage at point Vg1 don't go below V1 * R5/(R5+R8) = 2.44V the MOSFET will be OFF. So we can force this by switching ON the BJT or circuit can do it
    "himself" via D3 or D2 if the BJT is OFF.

    How you suggest me, how to replace the BJT with a AND gate.

    Thanks & regards,
    Vivek Alaparthi
     
  4. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Here is one way that should work.
     
  5. vivek20055

    Thread Starter Member

    Nov 4, 2012
    88
    0
    Hello,

    I have been thinking of the connection to the gate drive and the possibility of shutting the device off.
    Instead of the BJT used now I tried to remove the two NPN transistors and use a AND gate (74V2T08) for the inputs. The and gate and the resistor after the diode should then both be connected to 5V instead of 12V.



    Thanks & regards,
    Vivek Alaparthi
     
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