CE Amplifier in Spice.

lord loh. said:

audioguru said:

lord loh. said:

I have seen FFT graphs in swCAD could never interpret them. What are they for?

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They show all harmonics of a signal. look at the sine-wave input signal which doesn't have any harmonics.

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This is what I saw when I tried to get the FFT of a Sine wave... I expected a single peak. Or have I made a mistake...

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It looks to me like your vertical scale is FAR too big, why would you want a scale that goes down to -300dB?.

I might also make my usual comment about simulators?, have you considered doing electronics rather than computer games?.

Nigel Goodwin said:

It looks to me like your vertical scale is FAR too big, why would you want a scale that goes down to -300dB?.

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I did not se the scale... It was what appeared when I simulated...

Nigel Goodwin said:

I might also make my usual comment about simulators?, have you considered doing electronics rather than computer games?.

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If I compute the fourier series of a pure sine wave I shall still get a A0 term (The DC component) and a series of sines and cosines.

Nigel, What do you suggest I do to learn the use of FFT?

Stupid sim program and stupid me. I corrected the scales but the FFT still didn't look correct. Then I stupidly set the number of data points to max and the darn thing hyjacked my pc and it went beserk for a long time. I think it tried to use 120GB of my hard drive before I stopped it!