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Variable Capacitor Replacement? Answered

Do you think it would be possible to substitute a variable resistor and a normal capacitor for a variable capacitor?

The way I figure it is that a variable capacitor is supposed to adjust how fast said capacitor charges and discharges, wouldn't a variable resistor and a normal capacitor also function like this?

I'm working on an idea for a small am radio, and looking to substitute these parts. Could it work?

Thanks

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3 Replies

verence (author)2012-05-24

No, for a (very) limited number of circuits, it might work, kind of - for a very limited definition of 'work'.

If you don't want to learn more:
No, doesn't work this way, sorry.

If you want to give part of your soul to the imaginary wisdom:
It will not work, because a resistor has a real resistance while a capacitor has more, it has an impedance. That is a frequency depending kind of resistance. That is, for a single given frequency, you might replace a capacitor with a combination of a resistor and another capacitor. But not for any frequency.

If you want to spent some time (well, okay, a lot of time) with learning about the imaginary part of impedance and mathematics and such, you might add a new dimension [pun intended] to your knowledge.

lemonie (author)2012-05-24

No, they don't work like that, which is why these components get used as they are used.

L

steveastrouk (author)2012-05-23

No, you misunderstand completely capacitor action. The capacitor forms part of a tuned circuit.