In this article I tear down a 4-port USB charger of puzzling origin. 2 counterfeit chargers I examined earlier in design and manufacture, but considerably below the quality of name-brand chargers. 2 counterfeit chargers, but considerably lower fpga bitcoin mining diy than name-brand chargers. The charger provides more filtering than basic chargers, from the large input choke to the multiple output inductors.
It includes X and Y capacitors for filtering. The charger looks mostly safe, although it doesn’t have UL certification and I suspect it would fail certification. What software do you use to generate the schematic figure? I’m working on DIY solar chargers and inverters, and this is a really helpful article, full of good practical info.
I found the voltage control feedback circuit interesting. The zener diode acts like a voltage controlled SCR. When the voltage reaches the threshold, it clamps down and sends a pulse over the opto isolator. When the PWM chip gets many of these pulses, duty cycle decreases.