This is topic Simplex Hi Speed Intermittents. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Randy Bowden (Member # 587) on 09-24-2001, 01:02 PM:
Could someone please explain to me the practical aplications
for the Simplex Hi Speed intermittent. What were these things used for? I'm assuming they run at a higher frame rate, anyone know what that might be? I have rebuilt hundreds of Simplex intermittens and a couple of these things so far and am wondering if I should continue to convert them to a standard set up or keep with the high speed parts. Are these things obsolete. A little help please. Thanks
Randy
Posted by John Pytlak (Member # 331) on 09-24-2001, 01:10 PM:
The "high speed" or "drive-in" intermittents pulled the film into position faster, allowing the use of a smaller shutter blade to put more light on the screen. A typical "Geneva" starwheel intermittent takes 90-degrees of rotation (4:1 intermittent)to pull the film into position, whereas a "high speed" movement only takes about 72-degrees (5:1 intermittent). The downside is the additional mechanical components, increased noise, and increased stress on the sprocket teeth and film perforations due to the higher accelerations. The increased strength and durability of today's polyester film base helps reduce the risk of perforation damage.I suggest keeping the high speed linkage, and using those intermittents for applications that need the increased light (drive-ins and really large indoor screens).
Kodak was recently granted a patent on a new "Geneva mechanism and motion picture projector using same" (US Patent 6,183,087 , February 6, 2001 ) that modifies the starwheel and cam to achieve a much faster pulldown WITHOUT additional linkages:
Kodak Patent on New Intermittent
This Kodak invention will allow much greater light efficiency with a simple intermittent mechanism. The extra efficiency can be used to increase screen luminance, or allow the use of a three-blade shutter on larger screens, greatly reducing flicker. The Kodak prototype starwheel and cam were easily retrofit into existing intermittents like the Century.
------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Posted by Randy Bowden (Member # 587) on 09-24-2001, 01:39 PM:
John.
Thanks for the Reply. I will go ahead and do the rebuild with the High speed parts. These intermittents could definitely come in handy for the Drive in theatres that we service.
Posted by Mark Gulbrandsen (Member # 72) on 09-24-2001, 05:11 PM:
Randy, the high speeds are quite good. Their main problem was back when everyone was still using cement splices. The acceleration is so fast(5 to1) that it would pull the splices apart. Many were converted to regular speed d(3 to 1) due to this problem. Later when tape splicers hit the market it was really too late to save the HS pulldown intermittent. I have done quite a few projection jobs with high speed machines that I had at one time. Also I notice a definate improvement in on screen steadiness and apparent sharpness in the projected image. The best place to see this is in the rolling titles at the end of a feature. They appear unusually clear for some unknown phenomona. Parts are no longer available and you should use a low inertia alumnium sprocket to prevent excess weat to the moving parts. With the advent of polyestar film, the HS movement should really become compnplace today. Perhasp with Kodaks new designs that can be retrofitted into a Century easily it will happen. But I'm sure Kodak will want a premium for the parts too.
Mark @ GTS
Posted by Paul G. Thompson (Member # 655) on 09-24-2001, 08:02 PM:
Mark, you were right about them pulling cement splices apart. They also devoured single-sided tape splices, too! 
Paul
Posted by Josh Jones (Member # 447) on 09-24-2001, 09:02 PM:
I received info today on the brenkert bx90 telecine projector from our Mr. Sprague friend. It contained no shutter, no shutter compensator, but did contain a high speed modified movement, which did appear to be self contained and enclosed. more details when I get a chance to read the 25 pages or so of goodies I got in the mail today.Josh
Posted by Christopher Seo (Member # 7) on 09-25-2001, 06:22 AM:
Randy,For a handful of old topics on this subject just do a search for "high speed pulldown".
Posted by Robert Throop (Member # 61) on 12-03-2003, 01:30 PM:
Last week I replaced an intermittent in a Simplex XL. After changing the movement there was a travel ghost that could not be adjusted out. We realized that this was a high speed intermittent and replacing the shutter blade cured the problem.
This projector is installed in an art museum and was one of a matched pair of XL's installed in 1960. This was the original intermittent. This was a non critical installation and originally had Peerless Magnarcs. Now there's a Xenex 2 and a platter. I'm baffled as to why the hi speed movement was purchased. The other machine is long gone so we can't look at that intermittent.
Are Hi Speed parts still available?
I've been in this business since 1965 and this is the first one I've come across.
Posted by Jason Burroughs (Member # 68) on 12-03-2003, 02:10 PM:
Correct me if I'm wrong, but wouldn't a High-Speed intermittant potentially produce LESS shutter smear than a standard intermittant witht he same shutter in place?
Posted by John Pytlak (Member # 331) on 12-03-2003, 03:08 PM:
I think Mr. Throop replaced a high speed (5:1) movement with a standard (4:1) movement, so the shutter blade had to be increased from about 72 degrees to 90 degrees coverage.
Although high speed intermittents usually were used to obtain better light efficiency for drive-ins and really large screens, perhaps the museum needed more light on the screen from the Peerless Magnarc.
Posted by Mark Gulbrandsen (Member # 72) on 12-03-2003, 07:13 PM:
For unexplained reasons I've always noticed far better image definition when projecting with a high speed movement. Sharper, steadier, etc. There is a BIG difference. A high speed movement and the correct shutter blade and the machine will typically run around 70+% light efficiency.
Mark @ CLACO
Posted by Justin West (Member # 920) on 12-04-2003, 04:01 AM:
Is there a mark or catalog number ON the intermittent that distinguishes itself as a Hi-Speed variety...just in case I were to come across it in a pile of old projector parts... ![[Confused]](confused.gif)
Thanks!
Posted by Mark Gulbrandsen (Member # 72) on 12-04-2003, 08:27 AM:
Even without taking it apart its easy to tell a HS movement. grey in color Low INertia Almunium Sprocket...usually, unless someone has replaced it with a steel one which is incorrect. These Low Inertia sprockets are still available from LaVezzi (416DG31 I think). The cam is also mounted to the outboard cover and the end of the cam bushing is visible from the front slightly to the lower left of the sprocket. The flywheel is a bit thicker and has a small taper to one edge of it. It will also have a very low and totally different type of serial number than a regular movement.
Mark @ CLACO
Posted by Randy Bowden (Member # 587) on 12-04-2003, 07:13 PM:
Robert,
If you need hi speed parts I do have a few. You could also try wolk for parts, or I could rebuild it for you. The shaft & Gear are different than the standard G-1836 the part # is G-4128 the same starwheel is used, the cam is part # G-4131