Click here to purchase the entire book in PDF format. Voltage Follower Figure 2.67: An op amp in a voltage follower configuration. There is a special case of the non-inverting amplifier configuration whish is used frequently in audio circuitry to isolate signals within devices. In this case, the feedback ``resistor'' has a value of 0 $\Omega$ - a wire. We also omit the connection between the inverting input leg and the ground plane. This resistor is effectively unnecessary since setting the value of Rf to 0 $\Omega$ makes the gain equation go immediately to 1. Changing the value of R1 will have no effect on the gain, whether it's infinite or finite, as long as it's not 0 $\Omega$ . Omitting the R1 resistor makes the gain value infinity. This circuit will have an output which is identical to the intput voltage, therefore it is called a voltage follower (also known as a buffer) since it follows the signal level. The question then is, ``what use is it?'' Well, it's very useful if you want to isolate a signal so that whatever you connect the output of the circuit to has no effect on the circuit itself. We'll go into this a little farther in a later chapter.