Based on Doppler radar principle, BB-200 provides a compact and reliable method of detecting a person approaching an exhibit. Unlike passive infra-red (PIR) detectors used in burglar alarms and driveway lights, the low power radar beam may be aimed to cover a specific area. Also, range, or sensitivity, is easily adjustable from approximately 3 to over 15ft (1 to 5m). The result is that the exhibit is started only when a person is within the appropriate range. A switch-selected option reduces the possibility of activation when a person walks away from the BB-200, making it more attuned to a person approaching. BB-200 operates from 12 to 24V, either AC or DC, drawing 100mA. If this power is not available from elsewhere in the exhibit, a wall mount plug-in transformer, Model ATW-1220, is available, capable of power up to 10 BB-200s. In general, BB-200 should be mounted above and aimed at, the area to be covered. A green LED light visible on BB-200 lights when motion is sensed, aiding in adjustment process. Prior to final mounting it is recommended that the BB-200 be powered up and temporarily placed in the proposed location to ensure proper operation. BB-200 may be mounted behind common non-metallic building materials such as plywood, MDF, plexiglass or drywall.