220VAC to 8VDC 24W Flyback Switching Power Supply

sam.moshiri · July 2, 2023

The most important part of any electronic device is the power supply section. Any instability or malfunction in this part causes the device to stop its operation or show weird behavior. In this article/video, I introduced an AC to DC Flyback Switching power supply that converts 220V-AC to 8V-DC, which can be used in a variety of applications. The 8V selection for the output makes this supply friendly for any type of linear regulator.

The maximum power delivery of this power supply is 24W, which means it can handle 3A at 8V output. The controller chip is DK125, which does not need any external supply, a startup resistor, or even an auxiliary winding on the transformer. The transformer's ferrite core is RM8, which differs from most supplies using EE or EI cores. A small potentiometer allows you to adjust the output voltage and set it to 7.5 to 8V.

For the schematic and PCB design, I utilized Altium Designer 23 and shared the project with my friends for feedback and updates using Altium-365. The fast component search engine, Octopart, proved invaluable in quickly obtaining component information and generating the Bill of Materials (BOM). To ensure high-quality fabricated boards, I sent the Gerber files to PCBWay.

I tested the board for voltage drop and current delivery, output noise, and load step response. I used the Siglent SDL1020X-E DC Load, Siglent SDS2102X Plus oscilloscope, Siglent SDM3045X multimeter, and Siglent CP4020 current probe to perform all tests. I am confident that this circuit will meet your requirements for a compact and efficient power supply, providing reliable performance on your electronics bench.