no neutral wall switch

hi,
The schematic is correct. One condition to make it work is that it requires a load across TP1 and TP2 on the schematic. Without the load, it won't work as there is no path to close the current loop.

Assuming there is a load, once the relay turns ON, then the energy will come from the regulator circuit using Q2.

Of course I assume that the bulb is between terminals tp1 and tp2, and I guess how u1 works, while rl1 is open, but when rl1 is closed and the bulb turns on, I do not understand the regulator conformed by Q2.... j11-2 is live or neutral?

J11-2 is connected to live. For Q2, please read section 4.4 and 11.2 of the report.

hi, Thanks for the answers, I have other questions, how do you determine the number of turns of the primary winding of the transformer?, and the turns ratio of the secondary?...I have read some guides documents about flyback power sources, and how the ratio of turns is determined, and always stays in a close ratio of 1:1 ,2:1 even 4:1, but in this there is a primary of 100 turns and a secondary of 7 turns to get 3.8 volts, that would make a turns ratio of 14: 1... so I would like to know more about how you determined your design, to understand and apply the method to my needs, since I would like to get 5v to the output... thanks

hi,
I recommend using our PI Expert Online tool to help you design based on your chosen PI chip.
If you navigate to section 8 on DER622 report, you will see the sample PIXLS design.
When you use PIXLS, you need to decide what will be your VOR. This will determine your turns ratio since VOR is the output voltage reflected to the primary - VOR = VO*Np/Ns.
Higher VOR will increase the drain voltage but reduces the stress on the secondary rectifier.

https://piexpertonline.power.com/site/index

In case of RL1 relay off, how does D1 half bridge rectifier get the i/p voltage? LinkSwitch will be off in absence of power to primary, right?