Make this Universal UC3843 Flyback SMPS Circuit: Fully Customizable

In this video, you will learn how to design a complete universal input SMPS (85V to 265V AC) using the popular UC3843 current mode PWM controller. This step-by-step guide explains the full working of a 220V AC to 12V DC 5A flyback power supply, including circuit operation, transformer design, and practical component selection. We cover everything from input rectification, startup circuit, auxiliary winding operation, MOSFET switching, current sensing, and feedback regulation using TL431 and optocoupler. You will also understand how the same circuit works efficiently for both 110V AC and 220V AC inputs, and how the UC3843 automatically adjusts duty cycle to maintain a stable output. This video also includes detailed transformer calculations such as primary turns, secondary turns, auxiliary winding design, air gap selection, and wire thickness for a reliable 60W SMPS design. FULL PARTS LIST FOR 60W (12V 5A) UC3843 SMPS INPUT STAGE Fuse: 1.5A slow-blow NTC thermistor: 5D-9 or 5D-11 MOV: 471 or 561 Bridge rectifier: KBP206 or DB207 PRIMARY FILTER Capacitor: 220uF / 400V or 450V electrolytic Capacitor: 100nF / 400V polyester STARTUP AND VCC SUPPLY Resistor: 330k / 1W Capacitor: 47uF / 25V electrolytic Capacitor: 100nF ceramic Diode: UF4007 Zener diode: 18V / 1W PWM CONTROLLER IC: UC3843 (DIP-8) OSCILLATOR Resistor: 10k Capacitor: 1.5nF GATE DRIVE Resistor: 15 ohm Resistor: 10k CURRENT SENSE Resistor: 0.27 ohm / 2W Resistor: 100 ohm Capacitor: 1nF MOSFET MOSFET: 650V type Examples: STF7N65 or FQPF7N65 SNUBBER NETWORK Diode: UF4007 Resistor: 100k / 2W Capacitor: 2.2nF / 1kV TRANSFORMER Core: EE30 or EE35 ferrite core with bobbin Primary winding: 55 to 60 turns, 0.25mm to 0.3mm wire or 2 strands of 0.2mm Secondary winding: 7 to 8 turns, 0.8mm to 1mm wire or 2 to 3 strands of 0.5mm Auxiliary winding: 9 to 10 turns, 0.3mm wire Air gap: 0.5mm to 1mm Insulation: polyester or kapton tape between layers OUTPUT STAGE Diode: MBR20100 Schottky diode Capacitor: 2200uF / 25V electrolytic Capacitor: 100nF ceramic FEEDBACK SECTION IC: TL431 Optocoupler: PC817 Resistor: 1k Resistor: 8.2k Resistor: 2.2k Resistor: 10k (pull-up) Resistor: 10k (compensation) Capacitor: 100nF ADDITIONAL COMPONENTS Resistor: 100 ohm Capacitor: 1nF Optional: Resistor: 1k Capacitor: 1nF CONNECTORS AC input terminal block DC output terminal block MECHANICAL ITEMS Heatsink for MOSFET Heatsink for output diode Insulation sheet for MOSFET Thermal paste #SMPS #UC3843 #FlybackConverter #PowerSupply #ElectronicsEngineering #CircuitDesign #DIYElectronics #PowerElectronics #TransformerDesign #SwitchModePowerSupply #PWMController #TL431 #Optocoupler #MOSFET #ElectronicsProjects #Engineering #UniversalInputSMPS #12VPowerSupply #HighVoltage #FlybackTransformer #EECore #SMPSDesign #AnalogElectronics #ElectricalEngineering #HomemadeCircuits