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Is the connection to GND correct in the circuit?

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deralbert:
Hello, I generated a circuit for a SMPS (flyback topology) using Pi Expert from Power Electronics and then rebuilt it in Altium Designer (with small changes).

At the moment I have the following circuit (see [Modified_SMPS_TNY286PG.jpg]). In the original Pi Expert circuit, there was explicitly no GND at all (see [Original_SMPS_TNY286PG.jpg]). But I know that there must be at least one GND and that's why I added one at the most logical place: at the "minus" of the AC input, near the pin 1 of the connector J1.

Then I thought it would be very inconvenient to have a single GND while designing the PCB and hence added two more GNDs, in the middle and on the right of the circuit. It is still the same GND, right? Since I don't feel quite confident with the real electronic, I would like to ask: Is it allowed to do it so? Is my circuit still correct?

Thank you.

Benta:
"I would like to ask: Is it allowed to do it so? Is my circuit still correct?"
Only if you want to kill someone.
What you mean by "Ground" is properrly called PE or "protective earth" and has no place anywhere in your circuit.
The primary side (before the transformer) is controlled by the power company should be left as "L"/"N".
The secondary side is supposed to float and have no reference to PE or any other potential.

You know just enough to be very dangerous.

magic:

--- Quote from: Benta on January 24, 2023, 10:18:12 pm ---What you mean by "Ground" is properrly called PE or "protective earth" and has no place anywhere in your circuit.

--- End quote ---
To be fair it's not clear what exactly OP meant to do. So...


--- Quote from: deralbert on January 24, 2023, 10:06:20 pm ---But I know that there must be at least one GND and that's why I added one at the most logical place: at the "minus" of the AC input, near the pin 1 of the connector J1.

--- End quote ---
What makes you think you need "a ground"?
What do you mean by "a ground"?
What physical thing would this schematic symbol turn into when the PCB is built?



--- Quote from: Benta on January 24, 2023, 10:18:12 pm ---You know just enough to be very dangerous.

--- End quote ---
Well, there are people who don't even know that much ;D

wraper:
You broke the circuit since you shorted things that must not be shorted. Basically it's fine to place GND anywhere since it's just an arbitrary reference point. You can put GND in multiple places to instead of drawn connections to reduce their number. For the sake of PCB layout, it's better to just place GND on the negative output as you generally don't want an automatically drawn ground plane on a high voltage side. Also C4 ratings suggest an X type cap which is not suitable there. You need Y1 capacitor or two Y2 caps in series if your circuit does not connect output to mains earth terminal.

wraper:
BTW you forgot to connect primary winding. And you D6 should be a  Schottky diode for efficiency.

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