Dear sir , the circuit above can work normally?the ic1 is 7815, and the amplifier is LF353,
I don’t know the utility of the R1,R2 and C7, anybody help?

 

Since the 7815 is a fixed output voltage 3-terminal regulator, it appears that the designer of this circuit added IC1 and its surrounding components in an attempt to add a measure of noise/ripple cancellation on the output by feeding back the ac component present on the output of the supply.

The output of the LF353 opamp is driving the reference pin of the 7815 to achieve the noise/ripple cancellation.

hgmjr

 

Since the 7815 is a fixed output voltage 3-terminal regulator, it appears that the designer of this circuit added IC1 and its surrounding components in an attempt to add a measure of noise/ripple cancellation on the output by feeding back the ac component present on the output of the supply.

The output of the LF353 opamp is driving the reference pin of the 7815 to achieve the noise/ripple cancellation.

hgmjr

Why the need of that? Wouldn't a 7805 regulator already do that by itself?

I ask this since a regulator is practically a voltage follower (with the positive input of the internal op-amp connected to a voltage reference stabilized by a current mirror and with a pass transistor at the output), and as so it already has negative feedback.