Tone Capacitors

[Tweed]

How does a capacitor remove high frequencies from an AC circuit, like on an electric guitar? I know it's something to do with the charge/discharge rate of capacitor but can't reconcile how you get a similar signal minus high frequencies.

[bhg481]

The impedance of a capacitor is inversely proportional to the signal frequency. In other words, the higher the frequency of the signal the lower the impedance of the capacitor and high frequencies are remov more than low frequencies.

[Old_Geezer]

You need to look at filter theory. Capacitors in line will reduce lower frequencies as it tends to store and release charge and so is sluggish when current continually tries to pass through it, as is the case with lower frequencies. On the other hand a capacitor between the signal wire and "earth" will tend to short out the higher frequencies leaving just the lower ones.

[mibn2cweus]

Capacitors are reservoirs of charge of a limited and generally small capacity.. As a capacitor charges it build up a voltage opposite to the charging voltage. At higher frequencies the charging voltage changes faster so there is less time for a capacitor to charge and oppose current flow.

[Hymie]

To realise a very simple low pass circuit, imagine a resistive dividing network made up of two resistors of equal value (connected between the signal input and ground). The output of this circuit will be half in input signal from a d.c. to high frequency.

Now replace the resistor connected to ground with a capacitor; at d.c. and low frequency signals, the output of the circuit will be close to the input level (since the capacitor will have a high impedance at these frequencies). With a signal input of high frequency, the capacitance will be of low impedance, reducing the signal output by a factor of 10 or more depending on the capacitor value.

[Tweed]

Thanks a lot for your answers folks. I'm interested at what happens at the atomic level. As I understand it - low frequency signals in the tone circuit cannot pass to ground because capacitor has time to charge/discharge but for high frequencies the capacitor cannot charge/discharge quickly enough which has the effect of making the capacitor a conductor and sends high frequencies to ground.

[Hymie]

Theoretically it is electrons (and not atoms) that are moving within the circuit.

Your analogy of the capacitor working (at low and high frequencies) is correct.