Variable AC Voltage Source (Range: 0 to 12 volt).   AC Power Supply for Medical Equipment and Indirect Ophthalmoscopy. This is a high quality instrument, developed in St. Louis for faculty at Washington University, Dept. of Ophthalmology.  There is an orange indicator light which changes in luminance with voltage output.   Can be ceiling mounted (as photos demonstrate) and can be wired to turn off the room lights when the instrument or ophthalmoscope is removed from the carriage, if one desires.  

Unique variable power supply for medical equipment.  Designed to turn off the room lights when the medical instrument is removed from the carriage.  The room light control switch will handle 120 volt, 10 amp circuit.  It also has a manual switch that will bypass this power switch to the room to permit both to be on simultaneously.