February 16, 2009 Leave a comment
Lately, I’ve been getting inquiries on how to hook-up smoke detector(s) to an existing alarm panel or maybe to an autodialer. In most cases, the homeowner insists on the least amount of re-wiring ie no cutting walls to lay cable, etc. Well, Linear has the LNDXS73 Supervised Photeoelectric Smoke Detector which when paired with the LNDXR702 2 Channel Wireless Receiver will certainly be the perfect solution to this application.
When smoke is detected, the smoke detector sounds the local built-in siren. Twenty seconds after the local alarm sounds, the built-in transmitter sends a digitally coded wireless signal to the LNDXR702 receiver. The wireless signal will be repeated very 20 seconds as long as smoke is still present. The sensor can send three different codes : alarm, test and low battery status. The 3 volt lithium battery supplied with the transmitter can power the unit for up to 5 years. During normal operation, the green status indicator will blink every 10 seconds. Every hour the LNDXS73 will send a transmission status to the receiver. The hourly signal updates the receiver to the transmitter’s condition.
When the LNDXR702 receives an alarm signal from the smoke detector it will activate Channel 1 relay triggering a zone in the alarm panel. By monitoring the status transmissions of the sensor, the receiver can determine if the transmitter has a low battery or has been removed from the system. If the battery voltage drops below a preset level, the sensor will beep and the red indicator light will blink every 45 seconds. It will also send a low battery signal to the receiver that triggers the activation of Channel 2 relay. The LNDXR702 thus gives us an easy to install “bridge” to monitoring smoke detectors.
For applications that require monitoring without going through an alarm company, the SEE920 2 Channel Voice Dialer is the value choice. It can dial up to 4 numbers and can record a separate message per channel.