The **NET-35** is a popular series of miniature, open-frame AC/DC switching power supplies, most commonly manufactured by **Mean Well**. It is designed to provide triple-output DC voltages, typically used in industrial automation, telecommunications, and electronic instrumentation. --- ## 1. Core Specifications The "35" in the name represents the **35-watt** total power rating. Below is the general electronic profile for the common `NET-35B` variant: | Feature | Specification | | :--- | :--- | | **Input Voltage** | 85 ~ 264VAC (Universal Input) | | **Output Channels** | 3 (Triple Output) | | **Total Power** | 35 Watts | | **Cooling** | Free air convection | | **Efficiency** | ~78% to 82% | | **Protection** | Short circuit / Overload / Overvoltage | --- ## 2. Typical Output Configurations The NET-35 series usually comes in different versions (A, B, C, D) which dictate the specific voltages provided on the three rails: | Model | Output 1 (Main) | Output 2 | Output 3 | | :--- | :--- | :--- | :--- | | **NET-35A** | +5V / 4.0A | +12V / 1.0A | -5V / 0.5A | | **NET-35B** | +5V / 4.0A | +12V / 1.0A | -12V / 0.5A | | **NET-35C** | +5V / 4.0A | +15V / 1.0A | -15V / 0.5A | | **NET-35D** | +5V / 3.5A | +24V / 1.0A | +12V / 0.5A | --- ## 3. Key Electronic Components The internal circuitry of a NET-35 consists of several critical stages: ### A. Input Filter & Rectification * **EMI Filter:** Uses X and Y capacitors and a common-mode choke to reduce electromagnetic interference. * **Bridge Rectifier:** Converts the AC input into high-voltage DC. * **Bulk Capacitor:** Smooths the rectified DC before it enters the switching stage. ### B. Switching Stage * **PWM Controller IC:** The "brain" that regulates the duty cycle to maintain a steady output. * **Power MOSFET:** Switches the high-voltage DC at high frequencies (typically 65kHz) into the transformer. ### C. Transformer & Output * **Isolation Transformer:** Provides galvanic isolation between the AC side and the DC side while stepping down the voltage. * **Schottky Rectifiers:** Fast-recovery diodes on the output side to convert the high-frequency AC back to DC. * **Filter Inductors/Capacitors:** Low ESR capacitors that ensure low ripple and noise on the final output. ### D. Feedback Loop * **Optoisolator:** Sends a signal from the DC output back to the AC primary side to adjust the PWM if the load changes, ensuring voltage stability. --- ## 4. Usage Considerations * **Load Balancing:** Triple-output supplies often require a **minimum load** on the primary channel (usually the +5V rail) to ensure the other channels (12V/15V) remain stable. * **Form Factor:** It is an "open frame" PCB, meaning it lacks a metal enclosure. It must be mounted securely within a chassis to prevent accidental contact with high-voltage traces.