Wall Wart Question

[alfa88]

I'm reverse engineering a cheap wall wart and I think I have the circuit pretty well traced, One problem I have is some of the diodes have odd numbers D5, D6 and unlabeled 'C11PH' . Another question I have is where is the regulation coming from?

 

[duke37]

It looks as if the feedback is through the optical isolator. When Q1 on, it inhibits the oscillator (Q2)

 

[(*steve*)]

C11PH is almost certainly a 3V3 zener (or thereabouts)

 

[alfa88]

Thanks Steve. C11P is indeed a zener. I ran a check and had a WTH moment then I remembered I was dealing with a 12V wall wart not 5V. C11P is 11V. Rather than producing a separate board the Chinese company that made this simply exchanged parts to suit the higher voltage. The silkscreen on the board is for 5V.