I use a Sallen-Key bandpass filter in a project at university to isolate the 1kHz sinusoidal part of a square signal produced by a NE555 oscillator. Here is my circuit:
When I simulate it on PSpice, I get this:
But when I check the voltage with an oscilloscope on the real circuit, this is what I get (5V per square):
How can I explain the big differences in amplitude of the signal between simulation and reality ? Is that only losses in the NE555 and non-ideality of the opamp in the filter ?