I have a question about using TL431 and optocoupler as feedback. The attached circuit is as an example.
I understood like this.
The way the output signal is fed back to the input to regulate the output is
R8 and R10 are current regulating resistors,
and 2.5 V is fixed by a resistance of 2.4 K,
the reference voltage is formed by PC817,
Depending on the output being large or small from the number ① shown,
Is it correct that the current in the pc817 diode changes?