Page 6 - 2015-06

More light for older projectors

- Specto Light Source Modifications

Anthony Saffrey

Arguably, the Specto is one of the best projectors ever made for 9.5 mm silent films, so
it seemed a good machine to modify the light source on. The early model Spectos used
a 30 volt 100 watt lamp, which was superseded by a 110 volt 500 watt model in the 1950s.
As part of the modifications, I wanted to take out the wired dropper resistor and the
rheostat so it could be run off the mains voltage supply by means of solid state speed
control circuit.
First Steps
The first thing to do is the remove the lamp holder and the dropping resistor so as the
lamp house is clear. Next, remove the base cover and take out the rheostat, all of the
switches and the mains tapping so that the mains socket is left. Keep them for later – an
old shoe box is ideal!

You should now have a depopulated lamp and base area!

Making the lamp holder and dowser
This involves a fair a mount of metal-bashing but it can be done reasonably easy. I found
a length of aluminium angle 100 mm x 100 mm x 6 mm thick, which had to be cut to
length to form the lamp and dowser bracket – I found that 80 mm in length was enough.
One of the 100 mm angles needs to be cut down to 25 mm so as to not foul the shutter.
Note that the lower holes that previously held the lamp can, with some drilling and
tapping, be used as fixing points.

Any suitable reflector lamp holder can be used; I used an old Elf (Eiki) lamp holder
which had a burnt out base. The side wall needs to be cut out so as to aid cooling,
and a cut out for protruding lamp tip has to be made. More of that later.

6 REEL DEALS June 2015