The **NET-75B** is a 75W triple-output, enclosed-type AC/DC switching power supply manufactured by **MEAN WELL**. It is designed to provide three different DC output voltages from a single AC input, making it ideal for systems requiring multiple voltage rails (such as logic circuits and peripheral devices). ### 1. Key Technical Specifications Below are the primary electrical characteristics of the NET-75B: | Parameter | Output 1 (CH1) | Output 2 (CH2) | Output 3 (CH3) | | :--- | :--- | :--- | :--- | | **DC Voltage** | +5V | +12V | -12V | | **Rated Current** | 8A | 2.8A | 0.5A | | **Current Range** | 1A ~ 10A | 0.3A ~ 4A | 0.1A ~ 1A | | **Rated Power** | 74.4W Total | | | | **Ripple & Noise** | 80mVp-p | 120mVp-p | 120mVp-p | | **Voltage Adj.** | 4.75 ~ 5.5V | (CH1 only) | | --- ### 2. Physical and Operational Components The unit consists of several critical electronic sub-systems housed within a metallic ventilated case: * **Input Stage:** * Supports Universal AC Input: **85 ~ 264VAC** or **120 ~ 370VDC**. * Includes an EMI filter to minimize electromagnetic interference. * **Protection Circuitry:** * **Overload Protection:** Activates at 110% ~ 150% rated output power (Hiccup mode, recovers automatically). * **Over Voltage Protection:** Specifically for the 5V rail (CH1), triggering between 5.75V and 6.75V. * **Short Circuit Protection:** Protects all outputs from damage during a fault. * **Cooling System:** * Designed for **Free Air Convection**. It does not require an internal fan, which increases reliability and reduces noise. * **LED Indicator:** * Includes a "DC OK" green LED to visually confirm power output status. --- ### 3. Pin Assignments (Connector Terminal) The NET-75B typically uses a 7-pin screw terminal block for connections: | Pin No. | Assignment | Description | | :--- | :--- | :--- | | 1 | AC/L | AC Line (Hot) | | 2 | AC/N | AC Neutral | | 3 | FG | Frame Ground (Earth) | | 4 | DC OUTPUT -V | Common Ground (Negative) | | 5 | DC OUTPUT +V3 | -12V Output | | 6 | DC OUTPUT +V2 | +12V Output | | 7 | DC OUTPUT +V1 | +5V Output | --- ### 4. Typical Applications Because of its triple-rail design, the NET-75B is commonly found in: 1. **Industrial Automation:** Powering PLCs (5V) and sensors or actuators (12V). 2. **Telecommunications:** Providing split rails for signal processing. 3. **Test & Measurement:** Powering equipment that requires both positive and negative rails for Operational Amplifiers (Op-Amps).