HF500-15 12V 1A Flyback Switching Power Supply

Preface:
12V 1A, average efficiency approximately 79%. Uses HF500-15 chip, 12V 1A, EE19 transformer. This is my first time building an AC-DC flyback power supply. Most components are referenced from the datasheet, and the layout lacks sufficient safety margins.
High voltage is dangerous! This board is for my personal learning and sample making only. For further study, you can refer to Professor Sun's video tutorial for replication. (It uses the same chip.)
 
Characteristics:
- Input 90~260Vdc
- Compact design, although it can still be compact.
- Includes EMI shielding.
- Simple circuit, requires little prior knowledge, suitable for first-time flyback voltage design (referring to the chip).
- Full-load conversion efficiency approximately 84%
- Output 12V 1A. The
 
rectifier is too large; a small transformer
was soldered across it. I. Primary Inductance: I calculated the inductance using the formula provided in the datasheet, and it's similar to the reference design. II. Winding: Uses EE19 vertical 4+4 package. Due to insufficient transformer pins, the primary coil may need to be soldered; a 5+5 package is recommended. Because the initial winding was neat and close together, I got tired of winding and started winding haphazardly, resulting in some noise when powered on. III. Grinding the air gap: After winding the primary inductance to approximately 30mH, grinding the air gap took half a day, reducing it by about 1mm, resulting in approximately 3.6mH (50kHz). Temperature testing was conducted at room temperature (approximately 30°C), with sampling starting after half an hour of output at 12V 1A. The main heating element is a D4 SS310L, which will need to be replaced with an SB10100. Ripple testing will be conducted later. Efficiency testing was conducted using non-professional equipment due to budget constraints; results are for reference only. Sampling began after half an hour of warm-up. 1. Pin=1.94W. Vout=12.06V, Iout=0.1A, Pout=1.206W. Approximately 62.2% 2. Pin=7.45W. Vout=12.06V, Iout=0.49A, Pout=5.91W. Approximately 79.3% 3. Pin=14.65W. Vout=12.06V, Iout=1A, Pout=12.06W. About 84.7%