1 Channel 5V Solid State Relay (SSR) Module - 250V 2A Output - High Level Trigger with Resistive Fuse

Specifications:

• Relay Model: HFS4-2A-05DM
• Control Voltage (Input): 5V DC (Nominal)
• Trigger Type: High-Level Trigger (Logic 1 = ON)
• Load Voltage (Output): 100V to 240V AC (50/60Hz)
• Continuous Load Current: 2 Amperes
• Peak Current: 8A (Non-repetitive)
• Isolation Type: Optical (Phototriac)
• Switching Method: Zero-Cross Switching (Minimizes EMI)
• Protection: Integrated 2A Resistive Fuse
• Switching Time: < 1ms (Ultra-Fast)
• Logic Compatibility: 3.3V and 5V DC

Key Applications

• Smart Lighting: Create silent smart-home lighting controllers that don't make any noise when turning on or off.
• PID Heater Control: Use with an Arduino or PID controller to maintain extremely precise temperatures in reflow ovens or incubators.
• Photography Triggers: High-speed AC switching for studio lights and flash triggers where millisecond timing is critical.
• IoT Power Strips: Build compact, single-socket IoT power controllers for AC fans or small appliances.

Project Evolution

• Past Projects (Prerequisites): If you have built basic automation using standard blue mechanical relays, you have mastered "Basic Logic."
• Feature Upgrade: This SSR unlocks Advanced Power Management. You can now implement "Slow PWM" to control power levels in resistive heaters, a feature that would destroy a mechanical relay.
• Effort/Requirements: Beginner. Only requires 3 wires (VCC, GND, Signal) and standard Arduino coding knowledge.

Virtual Technician & Wiring

• VCC: Connect to 5V DC Power.
• GND: Connect to DC Ground.
• CH1 (Signal): Connect to GPIO (High = Relay Active).
• Output Terminals: Connect in series with the AC Live wire.
• ⚠️ SAFETY WARNING: This module is designed for AC LOADS ONLY. It will not switch or stop DC current (like 12V batteries). Always disconnect the mains power before adjusting wiring.

Package Includes: 

1 x 1 Channel 5V Solid State Relay (SSR) Module - 250V 2A Output - High Level Trigger with Resistive Fuse

Frequently Asked Questions (FAQ)

1. Can I use this for 12V DC LED strips?
   No, triac-based SSRs only switch AC loads. For DC, use a MOSFET module.
2. Does it make a 'click' sound?
   No, it is 100% silent.
3. Can I trigger this with a 3.3V Raspberry Pi?
   Yes, the High-Level trigger is compatible with 3.3V logic.
4. Is the fuse replaceable?
   No, it is a built-in resistive fuse for circuit protection. If it blows, the board likely protected your logic from a major short.
5. What is Zero-Cross switching?
   It switches the load only when the AC voltage is at 0V, which drastically reduces electrical noise.
6. Can it handle a 1000W heater?
   No. 2A at 240V is 480W. Stay below 400W for safety.
7. Why does my light flicker when the relay is off?
   Some low-wattage LEDs react to the tiny leakage current typical of all SSRs. Adding a small load resistor fixes this.
8. Does it need a heatsink?
   At 2A, the Hongfa HFS4-2A-05DM is designed to run cool without external fins.
9. Can I use it for PWM dimming?
   Only "Slow-PWM" (cycle times of seconds). It is not suitable for high-frequency dimming like a triac dimmer.
10. How many wires do I need for the input?
    Three: 5V Power, GND, and the Signal wire.
11. Is it faster than a mechanical relay?
    Yes, it switches in ~1ms, whereas mechanical relays take ~10ms.
12. What is a High-Level Trigger?
    The relay turns ON when the input is 5V (High) and OFF when it is 0V (Low).
13. Can I switch 110V AC?
    Yes, it works from 100V to 240V AC.
14. What is the quiescent current?
    Almost zero. It consumes power only when the relay is triggered (~12mA).
15. Is it safe to use with ESP8266?
    Yes, it is Probots™ Logic-Safe for ESP series chips.
16. Can I use it for an AC motor?
    Only very small motors (under 0.5A). Motors have high starting surges that can blow the 2A fuse.
17. Is it RoHS compliant?
    Yes.
18. What happens if I connect DC to the output?
    The relay will turn on but will never turn off until you disconnect the power.
19. What is the peak current rating?
    8A non-repetitive surge for a few milliseconds.
20. Can I mount multiple modules side-by-side?
    Yes, their compact footprint is designed for rail or board mounting.