Depending on the value of the component, resistors block electrical current.  This is exactly what potentiometers do as well, but those have a variable level of resistance.  Consequently, these are sometimes referred to as "fixed resistors."

These are only applied in a limited number of applications in most guitar circuit.  For example:

• Shock-proof - A high-value resistor is placed between the string ground and the guitar's output to prevent a guitarist from being electrocuted if the amp's ground is somehow interrupted.

• Brightness - A resistor can be added between the volume knob and the ground to increase the brightness (and even the overall signal output) by blocking part of the signal normally lost to the ground.

Commonly refered to as "caps," these store a small amount of charge, but in various guitar circuits, tey are used to alter a tonal range.  Some example applications include:

• Tone Control - A capacitor is usually soldered between the tone knob and the ground, and this sets which

• Varitone - A  rotary switch is used to select between a variety of caps in order to selectively  pull out and accentuate particular frequencies.

• Tone Switch - A simple type of a Varitone consisting of just two caps.  These are most commonly (read: almost exclusively) found on Gretsch guitars.

• Hi-Pass Capacitor - A very small gauge cap is attached in parallel to the volume knob to prevent the high frequency components of the signal from being selectively cut when the volume is turned down.

Cap codes: Some additional useful information.

To read the value on a capacitor, you need to understand that the first two digits are multipled by the number specified by the third digit.  Use the following code, and the value will be given in pico-Farads:

 

0  1 2 3 4 5 6 7 8 9

1 10 100 1,000 10,000 100,000 not used not used .01 .1

For example, if a capacitor says 223 is 22 with 3 zeros or 22,000 pF which is otherwise referred to as a .022 uF capacitor.

Additionally, there is sometimes a letter representing a tolerance code.  For example, J stands for a +/-5% tolerance.

These store electricity in a magnetic field,.  They are occasionally found in applications such as custom passive tone controls.  For example, many people include an inductor between a varitone and the ground of the circuit.