4-Channel Solid State Relay Module (AC to DC Control) – 3V-24V Wide Voltage, High/Low Level Trigger

SKU: FA2084-2
Control Input Voltage

100-240V AC, 50/60Hz
Load Output Voltage

3-24V DC (Wide Range, Auto-detecting)
Maximum Load Current

2A per channel
Channels

4 independent channels
Trigger Logic

High-Level or Low-Level (jumper selectable)
Isolation Voltage

2500V RMS
Switching Type

Zero-crossing solid state
On-state Voltage Drop

< 1.5V DC
Dimensions

Approximately 105mm x 85mm x 28mm

Product Description

The 4-Channel Solid State Relay Module (AC to DC Control) is a versatile and intelligent switching interface designed to safely control DC-powered devices and systems using AC mains voltage as the control signal. This innovative module allows you to use standard wall switches, door sensors, or other 100-240V AC signals to trigger low-voltage DC circuits, bridging the gap between high-voltage AC control systems and modern DC-powered applications. With an exceptionally wide 3-24V DC output range and selectable high/low-level trigger logic, it provides unparalleled compatibility for powering motors, LEDs, solenoids, and other DC loads directly from AC control sources.
Featuring advanced optocoupler isolation on all four independent channels, this module ensures complete electrical separation between the AC control side and DC load side, protecting sensitive DC electronics from AC line noise and voltage spikes. The solid-state design provides silent operation, fast switching speeds, and exceptional reliability with no moving parts to wear out. Whether you’re upgrading traditional AC control systems to interface with DC equipment, building automation systems that require mixed voltage operation, or creating safety interlock circuits, this module offers the perfect solution for reliable, isolated control between AC and DC domains.

Key Features

  • Bi-Directional Voltage Control:​ Use standard 100-240V AC signals to control 3-24V DC loads, creating seamless interfaces between AC control systems and modern DC equipment.
  • Wide DC Output Range:​ Supports 3-24V DC loads with automatic voltage detection, eliminating the need for multiple relay types for different DC voltages.
  • Dual Trigger Mode Selectable:​ Configure each channel individually for high-level or low-level trigger operation via convenient onboard jumpers for maximum application flexibility.
  • Full Optical Isolation:​ Advanced 2500Vrms optocoupler isolation on all channels protects DC electronics from AC line transients, noise, and potential ground loops.
  • Four Independent Channels:​ Control up to four separate DC circuits or devices from a single compact module, with individual status indicators for each channel.
  • Solid-State Reliability:​ No moving parts ensures silent operation, fast switching, and exceptional lifespan compared to mechanical relays.
  • Zero Voltage Crossing:​ Integrated zero-crossing detection minimizes inrush current and electromagnetic interference for cleaner switching of DC loads.
  • Universal AC Input Compatibility:​ Works with worldwide AC voltages from 100V to 240V AC at 50/60Hz, making it suitable for international applications.

Main Parameters

  • Control Input Voltage:​ 100-240V AC, 50/60Hz
  • Load Output Voltage:​ 3-24V DC (Wide Range, Auto-detecting)
  • Maximum Load Current:​ 2A per channel
  • Channels:​ 4 independent channels
  • Trigger Logic:​ High-Level or Low-Level (jumper selectable)
  • Isolation Voltage:​ 2500V RMS
  • Switching Type:​ Zero-crossing solid state
  • On-state Voltage Drop:​ < 1.5V DC
  • Dimensions:​ Approximately 105mm x 85mm x 28mm

Typical Applications / Usage

  1. Industrial Control Upgrades:​ Modernize existing AC-controlled machinery to operate 24V DC solenoids, sensors, or PLC input circuits without rewiring the entire control system.
  2. Smart Building Integration:​ Connect traditional 120/240V AC wall switches, timers, or occupancy sensors to control modern 12V/24V DC LED lighting systems, motorized blinds, or access control devices.
  3. Safety Interlock Systems:​ Create isolated safety circuits where AC-powered equipment status (like door switches or emergency stops) must control DC-powered alarms, indicators, or shutdown sequences.
  4. Mixed Voltage Automation:​ Build control panels that interface AC mains control signals with DC-powered devices in industrial, agricultural, or theatrical automation systems.
  5. Energy Management:​ Use AC power status (from solar inverters, grid sensing, or generator outputs) to control DC battery charging systems, DC loads, or monitoring equipment.
  6. Prototyping & Testing:​ Ideal for R&D applications requiring reliable isolation between AC control signals and DC test equipment or prototypes.
Implementation Guide:
  • Configuration:​ Set the trigger jumper for each channel to either “H” (High-level trigger) or “L” (Low-level trigger) based on your AC control signal characteristics.
  • AC Control Wiring:​ Connect the 100-240V AC control signal (e.g., from a wall switch, timer, or sensor) to the AC input terminals of the desired channel. Ensure proper polarity (Line/Neutral) if specified.
  • DC Load Wiring:​ Connect your DC power source (3-24V DC) to the DC input terminals, and connect your DC load (motor, LED strip, solenoid) to the output terminals of the same channel. The module will automatically detect and work with the supplied DC voltage.
  • Safety First:​ Always disconnect all power sources (both AC and DC) before making connections. Verify wiring with appropriate testing equipment and follow all electrical safety regulations for your region.
Q: How is this different from a standard DC-controlled SSR?

This module reverses the traditional SSR configuration. Instead of using DC to control AC (like most SSRs), this module uses AC to control DC. It allows AC control signals (like wall switches) to safely operate DC devices, which is perfect for modernizing systems or integrating DC equipment into existing AC control infrastructure.

Q: Can I use this module to control AC loads?

No, this specific module is designed exclusively for controlling DC loads (3-24V DC).​ The output is DC-only. For controlling AC loads with a DC signal, you would need our standard DC-to-AC SSR module.

Q: How does the wide 3-24V DC output range work?

The module automatically detects and adapts to the DC voltage you supply to the load terminals within the 3-24V range. This means you can use the same module to control 5V, 12V, or 24V DC devices without any configuration changes, as long as you provide the corresponding DC power supply.

Q: My AC control signal is from a standard 120V wall switch. Will this work?

Yes, perfectly.​ The module is designed for standard AC mains voltages worldwide. A wall switch provides 120V AC when closed (ON) and 0V AC when open (OFF), which the module can detect as a control signal. Just ensure you select the correct trigger mode (usually Low-Level for a switch that provides 0V when OFF).

Q: What is the advantage of the high/low-level trigger selection?

This allows compatibility with different types of AC control signals. High-Level trigger​ activates the DC output when AC voltage is present. Low-Level trigger​ activates the DC output when AC voltage is absent (0V). This lets you match the module to normally-open or normally-closed switches/sensors.

Q: What happens if I connect a DC load that requires more than 2A?

Exceeding the 2A per channel rating will cause the solid-state switch to overheat and fail permanently. For higher current DC loads, you can use this module to control the coil of a higher-capacity DC-rated mechanical contactor (relay), which then switches the high-current DC load.

Q: Can I use this with PWM (Pulse Width Modulation) signals to control DC motor speed?

No.​ This module is designed for on/off switching only. The zero-crossing circuitry and solid-state design are not suitable for high-frequency PWM signals required for speed control. For PWM motor control, you need a specialized DC motor speed controller.

Q: Is this product suitable for industrial control panel integration?

Absolutely.​ Its wide voltage compatibility, optical isolation, industrial screw terminals, and robust construction make it ideal for professional integration. It solves the common problem of interfacing legacy AC control systems with modern DC-powered equipment. We provide technical documentation, volume pricing, and customization options for OEM and industrial clients.

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