Mercury Motion Sensing Visitor Chime - 120° Wall-Mount Detection

The Mercury motion sensing visitor chime is a battery-powered alert device that triggers a ding-dong chime when movement is detected within an 8m range at up to 120° coverage. The unit mounts to a wall via an adjustable bracket that allows the sensor angle to be tilted to cover doorways, corridors or reception areas without fixed wiring.

Designed for retail entrances, office reception areas, stockroom doors and residential hallways where a discreet entry alert is needed, the chime operates on 2 x AA batteries (not included) and draws minimal standby current to extend battery life. The passive infrared sensor activates only when motion is detected within the coverage zone, sounding a brief two-tone chime audible across a typical room. A red LED on the front panel indicates power status, while a separate indicator shows battery condition.

The white ABS housing measures 66 x 39 x 106mm and weighs 95g including the bracket, making it suitable for plasterboard, timber stud or masonry wall fixing with the supplied screws. The 120° detection angle covers a typical doorway width when mounted at standard door-frame height (1.8-2m), with the adjustable bracket allowing fine-tuning of the sensor tilt to avoid false triggers from ceiling fans or air conditioning vents. The 5-8m effective range depends on ambient temperature and the size of the moving object — a person walking normally triggers reliably at 8m, while smaller movements may need closer proximity.

Product Manual

How long do the batteries last?

Battery life depends on the number of activations per day. In a typical retail entrance with 20-30 activations daily, 2 x AA alkaline batteries last approximately 6-9 months. The unit enters low-power standby between triggers to conserve charge. The LED indicator warns when battery voltage drops below usable threshold.

Can the sensitivity or chime volume be adjusted?

No. The detection sensitivity is fixed at factory settings to balance range and false-trigger avoidance. The chime volume is also fixed. The adjustable wall bracket allows angle adjustment to fine-tune coverage area without changing sensor sensitivity.

Does it work in all lighting conditions?

The passive infrared sensor detects heat signature changes from moving objects, so it works in darkness and normal daylight. Very high ambient temperatures (above 30°C) may reduce effective range, as the thermal contrast between a person and the background decreases.

What causes false triggers?

Common causes include pets passing through the detection zone, direct sunlight hitting the sensor lens, and air currents from heating vents or fans moving curtains or lightweight objects. Mounting the unit at 1.8-2m height and angling the bracket to avoid airflow paths reduces false activations.