Generate a Pulse Width Modulation/Oscillator

Discussion in 'Homework Help' started by awesome3000, Oct 24, 2011.

  1. awesome3000

    Thread Starter New Member

    Apr 7, 2010
    2
    0
    Hi everyone,

    I have been trying to solve this question (in the Attachment) about generating a PWM.

    first i want to understand is this an oscillator circuit but we added (R with vin).

    i think know how to analysis the oscillator but what is the difference when we include the vin and R , is it going to affetc the analysis quite alot,i mean there will be an inital voltage on capacitor?.

    i am thinking is that at positive terminal e+=V0*(R2/R1+R2),and current start to flow from vo through R and capacitor to ground plus some inital voltage across capacitor,hence at inverting terminal start increas in voltage till a point when the inverting becomes larger than positive terminal, then the state will change over and then capacitor start discharging through the R and vo to zener diode.

    in addition how we can design the value of R3.

    Any suggestions and any hints would be much appreciated.

    Thanks
    Sam
     
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  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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