The first stage in my design of a line level audio signal processing circuit is a non-inverting (op amp) voltage follower. The signal at input might be for example one channel of output of a CD player.
The voltage follower might be simply configured as shown at A in my attached diagram. Following the principle of less is better, this might be very acceptable as input impedance of the non-inverting input terminal of the follower is very high.
However, as shown at B in the diagram, often times the follower is shown with a resistor connected from the non-inverting input terminal of the op amp to reference potential. I've seen resistance of this resistor specified as 100 k Ohm. Why would this resistor be included?
Finally, a further embellishment as shown at C in the diagram, is a capacitor connected between the input signal jack and the non-inverting input terminal of the op amp. What this is for I would think is to block direct current where the external equipment and the circuit including the voltage follower have differing reference potential. Is the capacitor necessary for my circuit?
Thanks for your input,
Pete
The voltage follower might be simply configured as shown at A in my attached diagram. Following the principle of less is better, this might be very acceptable as input impedance of the non-inverting input terminal of the follower is very high.
However, as shown at B in the diagram, often times the follower is shown with a resistor connected from the non-inverting input terminal of the op amp to reference potential. I've seen resistance of this resistor specified as 100 k Ohm. Why would this resistor be included?
Finally, a further embellishment as shown at C in the diagram, is a capacitor connected between the input signal jack and the non-inverting input terminal of the op amp. What this is for I would think is to block direct current where the external equipment and the circuit including the voltage follower have differing reference potential. Is the capacitor necessary for my circuit?
Thanks for your input,
Pete
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