FCB18 Twilight Relay
Automatic light sensor relay for dusk-to-dawn control. Detects ambient light levels (Lux) and automatically switches loads on at darkness, off at daylight. Wide voltage AC/DC 12-240V with adjustable sensitivity for street lights, billboards, signage, and outdoor lighting systems.
What is a Twilight Relay?
A Twilight Relay (also called Light Sensor Relay or Dusk-to-Dawn Relay) automatically controls lighting based on ambient light levels. When natural light drops below a set Lux threshold, the relay activates connected loads. When daylight returns, it switches the loads off.
Fiicco FCB18 Twilight Relay provides reliable automatic lighting control for outdoor applications. The built-in light sensor detects ambient illumination, and the adjustable sensitivity dial allows customization for different environments - from bright outdoor areas to shaded locations.
How It Works
Simple automatic lighting control based on ambient light detection
Light Detection Principle
The FCB18 uses a built-in or external light sensor (photoresistor) to detect ambient light intensity measured in Lux.
- ON: When light drops BELOW set Lux value
- OFF: When light rises ABOVE set Lux value
Control Modes
FCB18 offers two basic control modes for automatic lighting:
Auto Mode: Fully automatic operation based on ambient light. No manual intervention needed.
Manual Override: Force ON or OFF regardless of light level for testing or maintenance.
Typical Lux Levels:
Key Features
Designed for reliable automatic lighting control
Adjustable Lux
Set ON threshold from 5-100 Lux for precise light detection
Wide Voltage
AC/DC 12-240V universal input for global compatibility
Time Delay
Built-in delay prevents false triggering from temporary light changes
LED Indication
Green LED for power, Red LED for relay status
Technical Specifications
FCB18 twilight relay specifications
Supply Voltage
AC 230V / DC 24V / AC/DC 12-240V
Power Consumption
AC 3.5VA / DC 2.0W
Output Contact
1× SPDT 16A
Lux Range
5 - 100 Lux
Voltage Tolerance
-15% ~ +10%
Dimensions
90×18×64mm
Temperature
-20°C ~ +60°C
Weight
75g
Wiring Terminals
Terminal configuration for FCB18 twilight relay
Power Supply
Control voltage input
Light Sensor
Ambient light sensing
Output Contact
SPDT relay output
Sensor (Accessories)
Optional external light sensor for remote mounting
FCB-PB External Light Sensor
20cm cable included with the main body. Allows remote sensor mounting for better light detection positioning.
Included with FCB18Common Applications
Ideal for automatic dusk-to-dawn lighting control
Street Lighting
Road, highway, and pathway lights
Billboards & Signs
LED billboards and advertising signs
Outdoor Lighting
Garden, parking lot, and terrace lights
Security Lighting
Motion-activated perimeter lights
Facade Lighting
Building exterior and monument illumination
Industrial Yards
Warehouse and factory perimeter lighting
FCB18 Twilight Relay
Automatic light sensor relay for dusk-to-dawn control
FCB18- W
AC/DC 12-240V Wide VoltageThe FCB18 Twilight Relay automatically controls lighting based on ambient light levels. Perfect for street lighting, billboards, signage, and outdoor area lighting. Energy-efficient automatic operation with adjustable sensitivity.
View Product DetailsWhy Choose Fiicco FCB18?
Compare our advantages against typical market alternatives
Fiicco FCB18 Advantages
- Wide voltage AC/DC 12-240V input
- Adjustable sensitivity 5-100 Lux
- Built-in time delay prevents false triggering
- LED power & status indication
- External sensor included (FCB-PB)
Typical Market Alternatives
- Limited fixed voltage options only
- Non-adjustable or narrow Lux range
- Prone to false triggering from car headlights
- No status indication
- External sensor sold separately
Frequently Asked Questions
What's the difference between FCB18-A, FCB18-D, and FCB18-W?
FCB18-A operates on AC 230V only. FCB18-D operates on DC 24V only. FCB18-W (recommended) accepts AC/DC 12-240V, making it suitable for global markets with different voltage standards.
How do I set the Lux level?
The sensitivity dial on the relay allows adjustment from 5 Lux (very sensitive, activates in dim light) to 100 Lux (less sensitive, requires brighter conditions). For most outdoor applications, 10-30 Lux is recommended.
What is the time delay for?
The built-in time delay (Tt) prevents false triggering from temporary light changes like car headlights or clouds passing the sun. The delay ensures stable operation - lights won't flicker on/off during brief light fluctuations.
Can I use FCB18 for indoor lighting?
Yes, FCB18 can be used for indoor applications where automatic light control is desired, such as warehouses, offices, or commercial spaces. However, ensure the sensor is positioned to accurately detect the desired light conditions.
What's included in the package?
The FCB18 comes with the FCB-PB external light sensor (20cm cable) included with the main body. The sensor can be remotely mounted for optimal light detection positioning. No additional accessories required for basic installation.
Ready to Order FCB18 Twilight Relay?
Contact Fiicco for pricing, sample orders, or technical support. External light sensor included. We ship globally with full technical documentation and installation guide.