Variable Resistors find use in most circuit applications. They can be connected as a potentiometer to vary voltage or as a rheostat to vary current. Consider using a variable resistor in your audio projects to allow setting of gain and frequency response. Use a variable resistor in place of a fixed resistor in a circuit to give room for finer control of circuit parameters. for instance in a timer circuit a variable resistor can be used to allow for precise control of pulse duration or frequency.