I am moving away from my HLK-PM01 based power supply idea and looking at using an external 24VAC power supply to power both my garden solenoids and also the ESP8266 logic controller. I have found a circuit that is being used in a similar project but have some questions about design.

I have re-drawn the circuit using components I can source from LCSC shown below.

The design uses a half wave rectifier to supply a DC current to the LM2596 switcher circuit. Would it be better to use a SMD full bridge rectifier to supply the LM2596?

The 5V output will be used to power the relay coils and the separate 3.3v linear regulator will be used to power the ESP8266.

 

I would not go low cost on L2. The IC can deliver 3A and the inductor should handle that.
For D8, I would use 4 diodes but if cost is a real problem 1 will work.

 

That's what I thought, a full wave rectifier instead of half wave.

 

Just thinking also, should I be thinking about isolation? The 24VAC will come from a wall-wart style power supply most probably. If the transformer in that device happened to leak 240VAC from primary to secondary windings that means my whole project could be exposed to mains AC.