The ELK-930 performs three functions. It can detect ring activation from one or two doorbell buttons and a single telephone line. It conveniently isolates the voltage and current and produces an open collector (pull to ground) output which can be used to trigger an automation controller, relay, timer, etc. The circuit is pre-scored so that the individual detectors may be snapped off (separated) from each other.

The ELK-930 Doorbell Detector monitors the current draw of a doorbell and produces an open collector output when the pushbutton is pressed and the doorbell draws 900mA or more. This open collector output can be used to trigger an automation controller input that utilizes high to low switching (pull to ground) for activation. The ELK-930 Telephone Ring Detector monitors the voltage on the telephone line and produces an open collector output (pull to ground) when the telephone ringing voltage is approximately 50 Volts or greater. The output follows the ringing pattern.