square wave oscillator, threshold

Discussion in 'Homework Help' started by uofmx12, Nov 9, 2011.

  1. uofmx12

    Thread Starter Member

    Mar 8, 2011


    Square wave oscillator, can someone explain the threshold equation? Also, why only R1 and R2 used?
  2. JDT

    Well-Known Member

    Feb 12, 2009
    R only affects the charging/discharging time of C and therefore the output frequency. It does not affect the threshold.

    R1 and R2 function as a potential divider, so that when the output of the amplifier swings from V+ to V-, the voltage on V2 swings by a smaller amount.

    When the voltage on the capacitor (V1) reaches the threshold (voltage on V2) the output switches.

    Note that the amplifier output will not usually reach V+ or V-. There will be a small voltage drop. See the amplifier data.