Capacitor mini-tutorial.

[Muzza]

Couple of points for a diehard pedant as myself.

The insulated middle section of a capacitor is called the 'dielectric'.

The correct term for a polarised capacitor is an 'electrolytic' capacitor.

Other than that, your practical knowledge of the correct use of capacitors trumps my theory knowledge, so carry on Doc...

[DrNomis_44]

Couple of points for a diehard pedant as myself.

The insulated middle section of a capacitor is called the 'dielectric'.

The correct term for a polarized capacitor is an 'electrolytic' capacitor.

Other than that, your practical knowledge of the correct use of capacitors trumps my theory knowledge, so carry on Doc...

You're absolutely correct Muzza, I should have mentioned that the insulator is called the dielectric, and that the correct term for a polarized cap was an electrolytic, good call mate.


@ Simon Barden Cheers for adding that bit of electronics theory, that explains in greater depth what is going on with the tone controls of an Electric guitar, my take on the low-pass filter formed by the resistor and the capacitor is that it is acting as a voltage-divider, you have the pure resistance of the resistor combined in series with the impedance of the capacitor, except that the impedance of the capacitor is really resistance to A.C. signals.


The windings of the pickups, the tone and volume control, and the tone cap in an electric guitar are all part of an A.C. circuit, both the pickups (since they are comprised of a number of turns of wire around a metal core, effectively an Inductor), and the tone caps, exhibit something called an impedance, impedance is something which is similar to resistance except for one thing, it is dependent on frequency.

Since a pickup is effectively an Inductor, it's impedance will increase as the frequency of the A.C. flowing through it increases, on the other hand, the impedance of a Capacitor will decrease as the frequency of A.C. flowing through it increases.

Another thing that happens in A.C. circuits is a phenomenon known as Phase-Shift.


Here's something interesting that happens in an A.C. circuit, say for example we build a very simple series A.C. circuit, consisting of an Inductor and a Capacitor, if both the Inductor and the Capacitor have a value which exhibits the same impedance value at a particular Frequency, but exactly 180 degrees out-of-phase, the result is that the two impedances, being equal and opposite in phase, will tend to cancel each other out, and what's left will be the pure D.C. resistance of the circuit, not only that, the A.C. signal at that particular frequency will find it very easy to flow in the circuit, our simple series A.C. circuit is said to be resonating at that particular frequency.

Current-flow in an electrical circuit is rather like the flow of water through pipes, it will tend to flow through the path of least resistance.