5V Low-Level Trigger Solid State Relay (SSR) Module with Built-in Fuse (G3MB-202P)
The G3MB-202P 5V Solid State Relay (SSR) Module is a high-performance, spark-free AC switching solution designed for microcontrollers and embedded systems. Available in 1, 2, 4, and 8-channel board configurations, this module allows digital controllers—such as Arduino, ESP32, Raspberry Pi, and PIC microcontrollers—to safely control household AC appliances, lighting systems, and industrial loads up to 240V AC at 2A per channel.
Unlike traditional mechanical relay modules that suffer from contact wear, electrical noise, and loud clicking sounds, solid-state technology utilizes semiconductor switching to deliver completely silent operation, ultra-fast response times, and an extended operational lifespan.
Key Features & Technical Highlights
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Optocoupler Isolation: Provides complete electrical isolation between the sensitive micro-controller control circuit (DC side) and high-voltage AC loads (AC side) to prevent voltage spikes from damaging control electronics.
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Low-Level Active Trigger: Switches state when a LOW signal (0V – 2.5V) is applied to the signal pin, making it directly compatible with standard 5V and 3.3V GPIO logic outputs.
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Integrated Overcurrent Protection: Each individual output channel is equipped with a resistive safety fuse to safeguard the module and connected devices against load faults and short circuits.
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Zero-Cross Switching (G3MB-202P): Built-in zero-cross detection reduces inrush current during load activation, suppressing electromagnetic interference (EMI) and electrical noise.
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Industrial Terminal Blocks: Sturdy screw terminals on the output side ensure secure connection of high-voltage wiring, while standard male header pins on the input side allow quick connection using jumper wires.
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Status LED Indicators: Onboard LED indicators provide immediate visual feedback for power status and channel activation.
Technical Specifications
| Parameter | Specification |
| Input Control Voltage (VCC) | 5V DC |
| Control Signal Level |
Low Level: 0V – 2.5V DC (Relay ON)
High Level: 3.3V – 5V DC (Relay OFF) |
| Output Load Voltage Range | 100V – 240V AC (50/60Hz) |
| Continuous Load Current | 2A Max per channel |
| Relay Component | Omron / OEM G3MB-202P |
| Isolation Type | Phototriac / Optocoupler |
| Protection | Onboard Resistive Fuse per channel |
| Channel Options | 1-Channel, 2-Channel, 4-Channel, 8-Channel |
Pin Configuration & Wiring Guide
Input Side (Control Connections)
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DC+ (VCC): Connect to 5V power supply.
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DC- (GND): Connect to common ground (0V).
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CH1 / CH2 / CH4 / CH8 (IN): Signal input pins. Connect to digital GPIO pins on the microcontroller.
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Signal LOW (0V) => Relay Closes / AC Load Turns ON
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Signal HIGH (5V) => Relay Opens / AC Load Turns OFF
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Output Side (Load Connections)
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SW1 / SW2 (Screw Terminals): Connected in series with the AC hot line (Live wire) of the connected load.
Operating Precautions & Application Notes
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AC Load Only: The G3MB-202P SSR is designed strictly for AC loads (100V – 240V AC). It will not switch DC loads properly (a DC load will turn on once and fail to turn off due to the internal Triac holding current).
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Current Rating Limits: The module supports up to 2A per channel. It is ideal for small AC motors, solenoids, light bulbs, fans, and heating elements. Do not exceed 2A per channel to avoid triggering or blowing the internal resistive fuse.
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Safety Notice: Working with high-voltage AC mains power requires extreme caution. Ensure power sources are disconnected prior to wiring or handling the circuit board.
