Description
Struggling to hear your phone ringing in a loud factory, warehouse, or busy office? Or need a reliable visual signal for emergency phones where silence isn’t an option?
The Viking BLK-4 is a high-visibility LED strobe and beacon kit that lights up when an analog phone line rings, goes off-hook, or both. Designed and built in the USA, it’s perfect for the hearing impaired, high-noise environments, and adding clear visual notification to emergency phones in elevators, campuses, parking garages, and more.
Easy to install on any standard phone line or analog PBX station, the BLK-4 gives you flexible control with multiple flash patterns, brightness levels, and a handy disable input for two-button emergency phones. Everything you need comes in the box—including the blue SL-2 strobe, control module, 12VDC power adapter, gel-filled butt connectors, and a weatherproof single-gang mounting box.
Our Expert Take: If you need reliable visual line status in a tough environment, the BLK-4 is one of the most flexible and durable options on the market. For fully exposed outdoor use, we recommend stepping up to the BLK-4-EWP version with enhanced weather protection.
Key Features
- Bright 360° blue LED strobe with durable polycarbonate lens
- Four programmable flash patterns: Single, Double, Quad, or Flicker Flash
- 6 brightness settings for perfect visibility in any lighting
- Configurable to activate on ringing, off-hook (line in use), both, or contact closure
- SPDT relay contacts plus switched 12VDC output to power additional devices like cameras
- Disable input – ideal for two-button emergency phones (won’t trigger on “Info” calls)
- Selectable ring cadence mode keeps light flashing between rings
- Immune to shock and vibration – built tough for industrial use
- Strobe and control module can be mounted separately
- Includes weatherproof single-gang box, 16 gel-filled butt connectors, and UL-listed 12VDC power adapter
- Additional colored lens covers available separately (red, amber, clear, green)
Technical Specifications
- Power: 120VAC to 12VDC 500mA UL-listed adapter (included)
- Strobe Dimensions: 4.38″ diameter × 2.75″ deep (111 mm × 69 mm)
- Control Module Dimensions: 2.9″ × 2.1″ × 1.0″ (74 mm × 53 mm × 25 mm)
- Shipping Weight: 3.3 lbs (1.5 kg)
- Operating Temperature: -15°F to 130°F (-26°C to 54°C)
- Humidity: 5% to 95% non-condensing (BLK-4)
- Relay Contacts: SPDT, 1A @ 30VDC / 0.5A @ 125VAC
- Minimum Loop Current: 15 mA
- Minimum Ring Voltage: 25 VRMS
- Ringer Equivalence (REN): 0.5A
- Max Power Supply Run (CAT-5): Up to 475 ft with 4 pairs
- Max Strobe Wire Run (CAT-5): Up to 300 ft with 6 wires
- Flash Rate: 60 flashes per minute (default)
- Max Light Output @ 15VDC (Blue lens): 116 lumens
- Mounting: Surface or flush with included weatherproof box; ¾″ knockouts for conduit
- Connections: Color-coded wires with gel-filled butt connectors