Songle SRD 9V DC Relay 10A 250V AC/DC

The Songle SRD series is a family of compact, PCB‑mount electromechanical relays designed for reliable switching of AC and DC loads. Widely used in Arduino and Raspberry Pi projects, industrial control, and home automation, these relays are trusted electronics components for both engineers and hobbyists who need robust isolation between low‑voltage microcontroller logic and higher voltage loads.

🧰 General Characteristics

• Brand: Songle
• Series: SRD
• Nominal Current: Generally 10A
• Contact Configuration: Available in SPDT (Single Pole Double Throw) or SPST (Single Pole Single Throw)
• Coil Voltages: Offered in 3V, 5V, 6V, 9V, 12V, 24V, and 48V DC
• Contact Voltage Ratings: Up to 250V AC or 30V DC
• Form Factor: Compact design, suitable for PCB mounting

📊 Technical Specifications

• Coil Resistance: Depends on coil voltage (e.g., approximately 400Ω for 12V DC)
• Operate Time (max): 10 ms
• Release Time (max): 5 ms
• Dielectric Strength: 500VAC (coil to contact), 1000VAC (between contacts)
• Mechanical Life: 10 million operations
• Electrical Life: 100,000 operations (at nominal load)

⚙️ Applications

• Industrial Control Systems: Machine and motor control
• Home Automation: Lighting, heating, and cooling systems
• Security Systems: Alarm systems, security doors
• Automotive Applications: Electric windows, headlights
• Electronic Projects: Frequently used with Arduino, Raspberry Pi, and other microcontroller projects

✅ Advantages

• High Reliability: Durable, proven electromechanical design
• Wide Application Range: Suitable for both AC and DC loads
• Easy Installation: Convenient PCB mounting footprint

⚠️ Disadvantages

• Mechanical Wear: Moving parts can degrade over time
• Size: Larger than many solid‑state relays in some applications

🧪 Example Product: SRD-09VDC-SL-C

• Coil Voltage: 9V DC
• Coil Resistance: ~180Ω
• Nominal Current: 10A
• Contact Configuration: SPDT
• Operate and Release Time: 10 ms and 5 ms

🔧 Integration Tips for Arduino, Raspberry Pi, and Microcontroller Modules

• Drive the relay coil via a transistor/MOSFET or a ready‑made relay module; do not connect the coil directly to GPIO pins.
• Always include a flyback (freewheel) diode across the coil when using discrete components.
• Verify supply voltage and coil current capability; use separate supply rails or proper decoupling to prevent brownouts.
• Observe contact ratings and use snubbers/TVS for inductive loads to extend electrical life.
• Maintain adequate creepage/clearance on PCBs when switching mains‑level voltages.

Whether you are building an Arduino relay module project, integrating with a Raspberry Pi, or designing industrial control hardware, the Songle SRD series delivers dependable switching performance with a compact, cost‑effective footprint.