Loading / Overloading of Operational Amplifier Oscillator

Discussion in 'General Electronics Chat' started by paw, May 2, 2012.

  1. paw

    Thread Starter New Member

    Jan 11, 2012
    Hi All,

    Just wanted a few pointers on some confusion I'm having.

    Im building a RC phase shift oscillator, with 3 RC networks and 1 op amp.
    Now, the output of this comes directly from the output from the op amp. I now want to simulate a 1k load.

    Does this mean I tie a 1k resistor from the output of the op amp to ground?

    Also, I need to give a visual warning of an overload condition of the amplifier. What actually is overloading of an operational amplifier? Does it mean that the load resistance is too low therefore the load is trying to draw too much current? Does it mean that the op amp output voltage clips?

    If it is the former case, of the current being too high, then what value should I look for on the datasheet to make sure I dont exceed it and overload the amplifier?

    Thanks so so much in advance,
    Kind Regards,

  2. SgtWookie


    Jul 17, 2007
    Hello Paw,
    You really need to attach a schematic of your circuit that includes the values of the components being used. Without a complete schematic, about all we can do is make wild guesses while asking for a schematic.

    We don't know what the average output voltage will be from your oscillator. If it will be zero volts, then yes, your resistor would go between the output and ground.

    1k is rather a heavy load for a typical opamp - but you haven't documented which opamp you are using, so we can't tell you if it is too heavy or not.
  3. crutschow


    Mar 14, 2008
    The op amp data sheet will give the output voltage for a given load. Generally you don't want the output load (including any feedback impedance) to be less than that value. It typically also gives a maximum (short-circuit) output current.