When the radiation intensity exceeds a pre-set level, the green light goes out and the red light and buzzer begin to flash at a one second rate. The alarm is pre-set to trip at 2 mR/hr (user-adjustable). Both the high voltage supply for the Geiger tube as well as the low voltage power supply employs voltage regulation for maximum stability.
The sensitivity adjustment is the control mounted on the printed circuit board (screwdriver adjust). Turning this control CW increases the sensitivity. DISCONNECT POWER BEFORE REMOVING COVER OR ADJUSTMENT.
Remove the cover and screw the hardware into the wall through the large mounting holes at each end of the box.
Two spare lamps and a spare fuse are located inside the alarm box.