Hello! I am a college student who wants to get extra credit in my Electronics class (I need it desperately).I heard that in some circuits you can replace a capacitor with an inductor, so I wanted to do a experiement:-Build a standard common emmitter circuit with a capacitor-Build another common emmitter circuit with a equivalent inductor-Compare and contrast the responseI did a google search on how to replace a inductor with a capacitor in a circuit, but to no avail. I haven't found anything.Do any of you brilliant engineers know about this circuit technique? Can you direct me to more information on how to do this?Thanks!
The simplest circuit I could think of for an inductor/capacitor substitution is a simple RC lowpass filter, in which the signal is fed to a resistor in series with a capacitor, and the output is taken from across the capacitor. The same circuit using an inductor would be where the signal is fed to a resistor in series with an inductor, and the output is taken from across the inductor. Of course, the same concept would work in op-amp feedback elements. Perhaps a more important thing to consider is that a capacitor integrates current, whereas an inductor integrates voltage. So any circuit where you can convert a current to a voltage, acapacitor would need to be replaced with an inductor to obtain the same result. (And vice versa.) This seems to be the general answer to your question.
I believe that the substitution is real, but not literal - for example in op amp filters a feedback inductor is the same as a feed in capacitor, and so on. Perhaps at a certain frequency a capacitor will look the same as an inductor in a circuit, but it seems impossible to for a capacitor to replace an inductor across all frequencies. Then again, I'm still an undergrad, and perhaps in something like a dc oscillator, it could be done.
