L-1011 CPT Installation - Annunciator Lighting System

L-1011 BRT/DIM Light Bus Control

All of the Caution, Warning and Advisory annunciators and switchlights on the L-1011 can be switched between two illumination intensity modes. The two modes are BRT (Bright) and DIM. There are two switches for BRT/DIM selection in the cockpit. One switch is located on the overhead panel light controls and switches the pilots annunciators and the second switch is located on the Second Officers light control panel (as seen in the picture above) and controls the light intensity of annunciators on the flight engineer's station.

The BRT/DIM switch is an alternate action latching switch that controls a relay that switches the respective BRT/DIM LGT bus from 24V to 10V ... hence changing the intensity of the illumination. Below is a short video that shows the BRT/DIM logic implemented on the workbench using a SPDT 24VDC relay.