The **NET-35B** is a popular 35-watt, dual-output enclosed switching power supply (SMPS) commonly manufactured by Mean Well. It is designed to convert AC line voltage into regulated DC voltage for electronic circuits. ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Input Voltage** | 85 ~ 264VAC or 120 ~ 370VDC | | **Output CH1** | +5V DC / 0.5 ~ 4.0A | | **Output CH2** | +12V DC / 0.1 ~ 1.5A | | **Total Power** | 35 Watts | | **Efficiency** | ~78% | | **Protection** | Short circuit / Overload / Overvoltage | --- ### 2. Internal Electronic Components The NET-35B consists of several functional stages, each utilizing specific electronic parts: #### A. Input & Filter Stage * **Fuse:** Provides overcurrent protection at the AC input. * **Varistor (MOV):** Protects the unit from high-voltage surges or lightning strikes. * **EMI Filter (Chokes & X/Y Capacitors):** Suppresses electromagnetic interference to prevent noise from leaking back into the power grid. #### B. Rectification & High-Voltage Stage * **Bridge Rectifier:** Converts AC voltage into pulsating DC. * **Bulk Electrolytic Capacitor:** Smooths the rectified DC into a high-voltage (approx. 300-400V) steady rail. * **Switching MOSFET/Transistor:** Acts as a high-speed electronic switch that "chops" the DC voltage into high-frequency pulses. #### C. Regulation & Isolation * **PWM Controller IC:** The "brain" that regulates the duty cycle of the MOSFET to maintain stable output voltage. * **Power Transformer:** Provides galvanic isolation between the high-voltage AC side and the low-voltage DC side while stepping down the voltage. * **Optoisolator (Photocoupler):** Sends feedback from the output side back to the PWM controller while maintaining electrical isolation. #### D. Output & Filtering Stage * **Schottky Rectifier Diodes:** Convert the high-frequency AC from the transformer back into DC. * **Low-ESR Capacitors:** Filter the high-frequency ripples to provide clean DC output to the terminal blocks. * **Inductors:** Work with the capacitors to form an LC filter for further noise reduction. --- ### 3. Connection Layout (Terminal Block) The physical interface usually consists of a 5 or 7-pin screw terminal: 1. **L (Line):** AC Hot wire. 2. **N (Neutral):** AC Neutral wire. 3. **FG (Frame Ground):** Earth ground for safety. 4. **COM (Common):** The negative (-) return path for both 5V and 12V. 5. **V2 (+12V):** Positive 12V output. 6. **V1 (+5V):** Positive 5V output. --- ### 4. Safety and Cooling The NET-35B uses **convection cooling**, meaning it relies on the air flowing through its perforated metal enclosure. It does not have an internal fan, making it silent but requiring adequate ventilation space during installation.