What is the function of C3?

[samy555]

Hi all
the following circuit is from:
https://www.circuitstoday.com/lead-acid-battery-charger

I hope somebody tell me why C3??
thanks

 

[albert22]

C2 and C3 are recommended to prevent oscillation of the LM317 and somewhat improving transient response. The datasheet specifies .1uf for both of them.

 

[samy555]

Thank you very much
How it is somewhat improving transient response?

 

[Audioguru]

The LM317 does not respond immediately to a transient: an input voltage change or an output current change. It has a small delay. Then the output has a voltage spike that is reduced by the output capacitor as shown on its datasheet that you should look at!

 

[samy555]

thank you guru