Printed circuit board components are available in many different types to control and regulate electrical flow through a particular circuit. Resistors, capacitors, diodes, transistors, and integrated circuits (ICs) are the most common of all components used in almost every electronic device, from a cell phone to a handheld radio. These components must be placed in strategic positions along the printed circuit board's (PCB) surface to create a useful electronic circuit.
A resistor is a tubular component that normally has specifically colored stripes along its outside surface. Its main purpose is to stop excessive electrical current from entering a circuit area; each resistor can stop only a certain amount of current, based on the component's resistance rating. The outside stripes signify a resistance value that assemblers reference when building a PCB. Improperly placed resistors can result in damage to other circuit board components from high current flows.
Capacitors resemble small cylinders that normally protrude from a PCB's surface. These printed circuit board components use the cylinder to store electrical current; the capacitorallows some current to trickle from the storage area to create a steady power supply to the rest of the PCB. The electronic device as a whole may not work correctly if the capacitors are improperly placed. As a result of bad or improperly placed capacitors, the electrical flow through the device's circuitry can have large variations that cause component failure.
