Some of the 300-series Bell and Howell projectors are designed for AC/DC
use.  Also some of the Ampro projectors were.  You can tell because they
employ universal motors with electromechanical governor arrangements instead
of modern AC synchronous motors. 

Note that SOME of the 300-series projectors used power transformers for the
tube electronics, but most of them were hot chassis and just ran directly
off the power line.

This was a big deal in the 1940s when these were made, since a lot of these
were used by the military in places that may have had DC or 50 Hz mains.
However, since we live in an era where cheap inverters are available, there
is really no reason not to just use one today and make solid AC from your 
DC line.
--scott

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