Viking Loop Detector Board with on board 12 Volt Regulator The LDB-1 provides a loop activated contact closure when used in series with telecom devices on analog phone lines. The LDB-1 will initiate a dry relay contact on any off-hook condition. Alternatively, add the optional PS-2 power supply to provide switched DC power.The relay itself is phone line powered and does not need an external power supply. Because both TIP and RING currents flow through the relay, excellent line balance is maintained. Features Phone line powered Excellent line balance Optional PS-2 power supply for switched power Made in the USA 1 Year Warranty Specifications Dimensions: 47.6mm x 30.5mm (1.875in x 1.2in) Mounting: (2) #4 screws (not included) or foam tape (included) Added Loop Resistance: 40 ohms Maximum Loop Current: 125 mA Minimum Loop Current: 18 mA Operating Temperature: -26 to 54C (-15 to 130 F) Maximum Supply Voltage Input: 35 VDC Maximum 12V Supply Current: 500 mA with Longitudinal Balance: 63 dB minimum Maximum Contact Voltage: 200 VDC Maximum Contact Current: 500 mA Maximum Contact Power: 10 W Connections: 7 pin screw terminal block