IR Photorelay Alarm (490-0310) Features Faxback Doc. # 8662 The Radio Shack Safe House Infrared Photorelay/Alarm sounds a tone any time something blocks its invisible infrared beam. You can use the alarm across a doorway or any opening up to fifty feet wide. The alarm is virtually unaffected by room lights, indirect sunlight, or other light sources, so false alarms from these sources are not likely. To avoid problems, we urge you to read this manual completely before you install or use the alarm. The many special features listed below make the alarm easy to use in many different applications. Alignment Indicator - Helps you install and test your alarm. Three Alarm Modes - Lets you set the alarm so that when someone blocks the beam, the alarm can sound for 5 minutes, sound only while something blocks the beam, or sound an annunciator tone. Relay Contacts - Activate external devices, such as a security dialer or an alarm system. Sensitivity Control - Lets you adjust the alarm for best operation. Optional Battery Backup - Gives additional security by letting your alarm operate even when the AC power has turned off. 12-Volt DC Output Terminals - Let you connect an optional external sounding device. (LB/all-07/12/94)