Description
Need a simple way to trigger a strobe, camera, or indicator light the moment your analog phone line rings or goes off-hook? The Viking LDB-3 Loop and Ring Detector Board monitors your phone line and closes a relay contact the instant it detects ringing or an off-hook condition — no complicated wiring or programming required.
This compact board connects directly to any analog phone line via screw terminals and uses a built-in relay to activate external devices like strobe lights, beacon lights, security cameras, or tape recorders whenever ring voltage or loop current is detected. A switched 12VDC output (up to 0.35 amps) follows the relay activation, so you can directly power external devices without a separate power supply. Three onboard DIP switches give you full control over ring detection, off-hook loop detection, and ring cadence mode — letting the relay either follow the ring pattern or stay latched on between rings.
Common applications include phone-in-use indicators, emergency strobe triggers, security camera activators, and visual ring alerts in loud or industrial environments. The board mounts easily to any wall surface using the included foam tape and ships complete with a 12VDC power adapter.
Our Expert Take: The LDB-3 is especially valuable when paired with Viking's two-button emergency phones like the E-1600-20A. The built-in Disable input ensures that when a caller presses the "Info" button, the relay will not activate — meaning your emergency strobe or camera only triggers on actual emergency calls, not informational ones. That single feature makes this board far more useful in real-world emergency phone installations than a generic loop detector. If you need relay-based line monitoring for a visual alert system or camera trigger, the LDB-3 is a clean, affordable solution that's built and backed in the USA.
Key Features
- Monitors analog phone lines for ringing and off-hook (loop current) conditions
- Built-in relay activates on ring detection, off-hook, or both — fully configurable via 3 DIP switches
- Selectable ring cadence mode — relay can follow ring pattern or remain on between rings
- Switched 12VDC output (0.35A) directly powers external strobes, cameras, or indicator lights
- One set of NO (normally open) and NC (normally closed) relay contacts provided
- Disable input prevents relay activation during "Info" button calls on two-button emergency phones (e.g., E-1600-20A)
- Screw terminal connections for easy, tool-friendly wiring
- Wall mountable with included foam tape or screws (not included)
- Complete with 120VAC to 12VDC power adapter
- Applications include strobe/beacon ring indicators, security camera triggers, tape recorders, and phone-in-use lights
- Made in the USA with a 1-year manufacturer's warranty
Technical Specifications
- Power Input: 120VAC to 12VDC adapter (included)
- Switched DC Output: 12VDC, 0.35A maximum (follows relay activation)
- Relay Contacts: One set NO and NC
- Detection: Ring voltage and off-hook loop current
- Configuration: 3 DIP switches (ring detection on/off, loop detection on/off, ring cadence mode)
- Connections: Screw terminals
- Mounting: Wall mount via included foam tape or screws (not included)
- Country of Origin: USA
- Warranty: 1 year manufacturer's warranty