I was trying to make a function generator using op amps, and I am supposed to get square waveform as output of the second stage and a triangular waveform as the output of the first waveform. But when I simulate the circuit in LTSpice, I am getting a constant voltage of around 14 V as output. What am I doing wrong?enter image description here

  • \$\begingroup\$ The total simulation time may be too large compared to the period of the oscillations so, even if you used startup, the timestep may have gotten too large by the time the oscillations actually started, resulting in the solver thinking there are none, to begin with. Try simulating for 1m or so. Increase/decrease as needed. Or, don't use startup and add ic=1 to C1, e.g. the value will look like 0.1u ic=1 (startup acts on both supplies and they mey be too symmetrical for something unusual to ahppen). Yet another thing is you could use a different opamp. \$\endgroup\$ Dec 2, 2022 at 14:06

1 Answer 1


Just one change to make to get oscillations. The 2nd stage must not be an inverting amplifier, but a schmitt:
revised schematic


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