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Topic: Simplex E-7 Collectors
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Alastair Bowlie-Evans
Film Handler
Posts: 34
From: South Wales, Swansea
Registered: Jun 2014
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posted 09-16-2014 12:42 PM
That 'syncholight' was (possibly) a rip-off of the FP-20-S Philips Pulse-Lamp system, where a tiny 800W High-Pressure water-cooled mercury vapour lamp was driven by a 'rectifier' running 6 large thyratron valves synchronised to the int-movement by a taco-generator made out of a magnetic tape-head.....
The rectifier also contained much other electronics--all Tube/Valves, chokes transformers, caps etc, to amplify/process the pulses from the taco-generator--And also contained-- 4 car type Spark-Plugs!
Int flywheel had three cut-outs, so the lamp was fired three times per frame giving a flicker-free image--like a three blade shutter would.
--This system was available from Philips in the Late 50's and early 60's.
A local cinema here used a pair of FP-20-S, the Pulse-lamp machines until the mid 70's....
The FP-20 had no shutter, just the (pair) of lamps in a movable turret assembly, water-cooled, the water forming the 'earth' return path for the power to the lamp....
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Jim Cassedy
Phenomenal Film Handler
Posts: 1661
From: San Francisco, CA
Registered: Dec 2006
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posted 09-17-2014 11:22 AM
quote: Alastair Bowlie-Evans
That 'syncholight' was (possibly) a rip-off of the FP-20-S Philips Pulse-Lamp system, where a tiny 800W High-Pressure water-cooled mercury vapour lamp was driven by a 'rectifier' running 6 large thyratron valves synchronised to the int-movement by a taco-generator made out of a magnetic tape-head
Looking through very old SME and other cinema-related technical journals, I've
noticed that there seemed to be a fascination, almost bordering on
obsession, with inventing a "continiuous motion" projector, which seemed
to peak in the period between appx 1919-1939. The quest was fueled by
the somewhat accurate belief that it was the film trap & intermittent
movement that caused the most wear and damage on film prints.
There are dozens of articles detailing numerous designs that were proposed
and/or actually built & tried, using various combinations of either stobe
lamps or moving mirrors or lenses to achieve the end result.
None of them were really practical. Machines using moving mirrors or
lenses were mechanically complex and difficult to keep optically aligned.
In addition, all the extra optics reduced light through-put substantially
(remember, this was in the days before coated optics) and also introduced
optical distortion to the image which was quite noticeable on all but the
smallest of screens.
Stroboscopic lamps of the time were just not capable of putting out
enough light for anything larger than a small screening room size screen,
and the electronics of that period were large, expensive, and not
reliable enough for theatrical use. (Movies were 'big business' back then)
Stroboscopic lamps for television projectors, on the other hand, seemed to be
somewhat more practical, since they don't have to project onto a large screen.
In fact, a patent search I did turned up a number of patents for stroboscopic
television-film projectors designed by RCA and television pioneer Alan Dumont
going as far back as the mid 1930's.
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