This is topic The ZIPPER what is it, Is it the dowser? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Bill Langfield (Member # 818) on 09-05-2004, 01:54 PM:
 
I admit that may be a teaser question, but I'm serious.

My take on the 'zipper' is that it is the aluminum plate between the aperture and shutter blade.

Ok, thats the basic bit, but there are many more, things that allow/dis-allow images on screen.

Am I correct in naming these from lamphouse to outside the port glass?

Im mainly talking about the stuff in CAPS.

1. (Mirror,bulb,heatsheild)
2. The DOWSER (the thing that totally stops light/heat to projector)
3. The SHUTTER (the thing that supplies the 24x2fps)
4. The FIRE SHUTTER (the thing that stops the light/heat if the projector stops midframe)
5. The ZIPPER (or the zippy as the girls seem to call it)
6. (The aperture, The film, the lens, the port, the idiots throwing stuff at the port, the screen)

2 to 4 are what I'm wondering about. Above is what I CALL them.

But I've heard 'techs' call zippers, 'shutters', 'dowsers'.
In fact, I hear 2-4 get completely mix up by many, many people, but in the context of the discussion, ALMOST every time it can figured what part is being refered to. (Normally the 'zipper' jamming open or shut!!)

Why do Cinemeccannica call BOTH the dowser and Zipper a 'DOWSER'?
Who do some Film-Tech'ers refer to motorise dowsers? -What are those?
 

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Posted by Will Kutler (Member # 770) on 09-05-2004, 02:01 PM:
 
Zipper is the product name given to the Simplex projector-mounted change-over. Zipper is etched on the data tag. The other style of change-over was manufactured by Weaver. Both manuals are on Film-Tech in the Manuals Forum.
 

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Posted by Jon Miller (Member # 163) on 09-05-2004, 02:53 PM:
 
"Zipper" is the brand name of Essannay Electric, who was the main manufacturer of electric changeovers for several decades. Some of the units were labeled Zipper; others were OEM'd for the major projector makers and labeled as such.

Here are a few examples (on a Motiograph AAA, Simplex X-L, and Brenkert BX-60, respectively)...


 

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Posted by Phil Hill (Member # 371) on 09-05-2004, 02:56 PM:
 
A "dowser" is someone who uses a divining rod to search for underground water.

A "douser" is something that stops the light.

>>> Phil
 

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Posted by Bill Langfield (Member # 818) on 09-05-2004, 03:30 PM:
 
Thanks, Phil.

Sorry for the typo.

Got any info THOUGH?

All the the ITA Cinemecannicas arond hear have it spelt that way
(year I that it spet worng too)

Regards, Bill.

John,
Years, I have worked on CENTURIES forever, and seen all but the last zipper.

But my question is why do people not understand the difference between, shutter, zipper, dowser
 

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Posted by Phil Hill (Member # 371) on 09-05-2004, 03:35 PM:
 
Bill, I meant nothing specifically to you... it was just a general comment.

It's just another one on my *MANY* pet-peeves!

Jon: Thanks for those pics! I'm looking for a couple of 120vac SA-5'S if anyone has some in great condition!

>>> Phil
 

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Posted by Bill Langfield (Member # 818) on 09-05-2004, 03:42 PM:
 
Phil,
Im a no-body around here, you don't to to back down because I got upset.

But nice to see anyway!!
 

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Posted by Phil Hill (Member # 371) on 09-05-2004, 03:48 PM:
 
Well that may be true. BUT! Just cuz some dumbass mfg cannot hire some "knowledgeable" translators doesn't make it "right".

We here in the US speak English for the most part... followed by Spanish and Ebonics...

>>> Phil
 

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Posted by Brad Miller (Member # 2) on 09-05-2004, 04:05 PM:
 

quote:

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I'm looking for a couple of 120vac SA-5'S if anyone has some in great condition!

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Phil are you nuts? Those 3 changeovers pictured above have a slow and sluggish changeover mechanism which makes for sloppy looking changeovers. Get a Kelmar!

If you really want the name on there, ship them to me and I'll write "Simplex" on the Kelmar units for you with a marker.
 

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Posted by Jon Miller (Member # 163) on 09-05-2004, 04:22 PM:
 
I guess I got carried away with the "what is a Zipper" part of the thread. The "Zipper" term for electric changeover assemblies became quasi-generic in the same way "Xerox" became synonymous for photcopiers, "Kleenex" stood for tissues in general, and the British got the habit of calling any vacuum cleaner a "Hoover" and vacuuming, "Hoovering," much to the hidden delight and outward consternation of the trademark owners.

Anyway, I took another look at my X-L. From the lamphouse douser to the aperture, the layout is changeover douser -> shutter -> fire shutter. E-7s and Centuries, OTOH, are shutter -> changeover douser -> fire shutter. The arrangement seems to be largely determined by the shutter configuration.

Brad--you're right...slow, sluggish, and NOISY (on the X-L, anyway)! Bzzz-CLANK!
 

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Posted by Phil Hill (Member # 371) on 09-05-2004, 04:40 PM:
 

quote: Brad Miller

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Those 3 changeovers pictured above have a slow and sluggish changeover mechanism...

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quote: Phil Hill

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I like the "old" stuff for nostalgic reasons.

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Ummm, when did this age preference of yours change?
 

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Posted by Phil Hill (Member # 371) on 09-05-2004, 04:45 PM:
 
Oh My! YOU ***WILL*** PAY for THAT comment! HA!

I was talking 'bout "PROJECTION" equipment! NOT "other" Ummm stuff!!

Although, interestingly enuff... I AM looking for a Simplex PR-1014 "born" in 1986... Hubba Hubba!

>>> Phil
 

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Posted by Gordon McLeod (Member # 33) on 09-05-2004, 06:14 PM:
 
Phil if you want older get the original changeover that Kelmar copied it was I believe called a Thide electric changeover
 

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Posted by Antonio Marcheselli (Member # 373) on 09-05-2004, 06:34 PM:
 
I've heard that, at least on Cinemeccanicas, the dowaser is that thing that, when the projector stops or is stopped, fall down with its own weight and, when the projector starts, is lift up by a solenoid.

A zipper instead, is a faster device that can guarantee a better changeover, has a solenoid for open it and a solenoid to close it, very fast.

I've heard that, I'm not sure.

Bye
A
 

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Posted by Michael Cunningham (Member # 210) on 09-06-2004, 10:06 AM:
 
My understanding of the names of these items is as follows. HAND DOUSER : built into the very front of the lamphouse. Usually consists of a big plate of steel on a hinge with a big handle sticking out the side for the operator to rotate it into or out of the light path. CHANGE-OVER DOUSER : playing card sized chunk of metal mounted on a pivot between the shutter and aperture. Moved into and out of the light path by an electric solenoid mounted on top of the projector by means of a vertical metal rod. Usually activated by the automation or a control button. MOTORIZED, ELECTRIC or AUTO DOUSER : this usually refers to a motor having been mounted on the shaft of the above-mentioned hand douser. The motor is wired in such a way as to open the hand douser when the projector motor is running and close it when the projector motor stops. Mostly useful in theatres that leave their bulbs running all the time.

- Mike
 

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Posted by Tim Reed (Member # 137) on 09-06-2004, 10:22 AM:
 
Gordon is right about the Thide c/o's.

Anyone ever see the ones called Senator?

And, who can forget the good ol' crappy Weavers?
 

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Posted by Per Hauberg (Member # 529) on 09-06-2004, 04:10 PM:
 

quote: Antonio Marcheselli

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I've heard that, I'm not sure.

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And when You once have heard a Cinemeccanica do a c/o, You'll be sure to recognize it, even from first raw of the auditorium
 

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Posted by Frank Angel (Member # 248) on 09-06-2004, 04:47 PM:
 
Anyone know if they ever manufactured a change-over mechanism that uses 12VDC coils instead of 115VAC? I am told that to minimize any 60hz hum into the mag penthouse heads, for the time that the solenoid is engaged, albeit only a second or two, using DC coils instead of AC will help.

But then, if such a 12VDC zipper model is not commercially available, couldn't a full-wave bridged rectifier wired to the AC coils accomplish the same thing while still using the same coils and without changing any of the hardware? Rectifying the 115VAC would supply the coils with DC, unfiltered, yes, but much less chance of inducing any significant 60Hz hum into the mag heads. The only other alternative I see (if DC versions were never manufactured) would be to find replacement coils that physically can replace the existing AC coils.

I don't quite understand what is different in a coil that makes it work on AC or DC? Just the windings are different? It's not clear to if there is any reason why supplying 115VDC to the coil would make it not function properly, except that it might get hotter faster? But for such short bursts, that wouldn't matter, right?
 

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Posted by Paul Mayer (Member # 355) on 09-06-2004, 05:11 PM:
 
Without a current limiting load of some kind, such a coil would look like a dead short to DC. It would probably open any circuit protection before the plunger could move. With AC, the coil will at least have some inductive reactance to it, and therefore not be a dead short.
 

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Posted by Joseph Pandolfi (Member # 223) on 09-14-2004, 09:25 PM:
 
We still use the top one in the picture in two of the four Century's here. The other two have Kelmar's
 

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Posted by Josh Jones (Member # 447) on 09-14-2004, 10:23 PM:
 
*Fart*
 

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Posted by Ken Lackner (Member # 1002) on 09-14-2004, 10:29 PM:
 
Bill: Michael C. seemed to answer your question perfectly. Just to clarify what a motorized dowswer is: essentially it is an automatic "hand" dowswer that closes when the projector is not running. Theaters designed by Act III, and perhaps others, used vertically mounted bulbs that are on all day. To keep the changeover from burning up, the hand dowser would have to be closed during intermission. That's why they are motorized.

AFAIK, Zipper = changeover.

I have used autodouser synonymously with changeover. Is that incorrect, or is it just another case of one person calls it this, another calls it that, but both are right?

Interestingly, RGM automation labels the fuse for the changeover as SHUTTER. I never understood that. If you ask me, that is definitely WRONG. A shutter is a shutter. Period.
 

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Posted by Dan Lyons (Member # 1454) on 09-14-2004, 10:43 PM:
 

quote: Tim Reed

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And, who can forget the good ol' crappy Weavers?

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Not me! I have them at my theatre, along with icky RCA 1040's which have been leaking since 1947!

danny
 

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Posted by Randy Stankey (Member # 64) on 09-14-2004, 11:04 PM:
 
Correct me if I'm wrong but wouldn't putting a rectifier on an AC line still give you some amount of 60 cycle hum?

If you used a 1/2 wave rectifier, you'd get pulsating DC which would make almost as much noise as AC would. The electromagnetic field around the wires would still be expanding and collapsing 60 times per second, thus producing the possibility of interference.

If you used a full wave rectifier you would end up with rippling DC. No where near as much interference but, since there is an expanding and contracting electromagnetic field, there's still a possibility.

Now, I suppose you could isolate the rectifier from the area of the sensitive components by putting the rectifier in a metal box, some distance from the "danger zone" then running the wires with EMT/armored cable and ensuring the outside is grounded. But, then, again, if you used EMT/armored cable, you probably wouldn't have quite so much interference from AC anyway... No?
 

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Posted by Frank Angel (Member # 248) on 09-15-2004, 03:52 AM:
 
I think you're right about rectifying the AC, Randy; you would still have pulsing 60hz, but I am not sure if the intensity would much as full wave 115vac. But I think that it is not the AC lines running to the solenoid coils which induce the 60Hz into the mag heads but the energized coils themselves....little electromagnetic transmission stations they are. The change-over mechanisms sit right up there not more than 10 inches away from the mag heads. I would surmise that even if you had 24VDC coils and fully rectified DC, you would still get a big, noisy thud when the coil activated...I mean, that coil it's still a huge magnet that's just been energized and then collapses; that's got to be seen by any magnetic pickup, especially the four mag heads and the super high-gain amplification they need, as one massive thud. But maybe not a THUD coupled with an equally loud 60hz HUMMMMM for the duration you hold down the footswitch.

Obviously they couldn't figure out a solution when Altec designed the preamp system that was original with our system because they way they dealt with it was simple, the sound change-over button was a DPDT pushbutton. It was designed in such a way that as you pushed the switch in, the first contact that was made wasn't the sound circuitry but an 8 pole relay that shorted all channels to ground. The second contact which engaged about an eight of an inch further on the button travel, threw the actual sound change-over. If you hit the footswitch (solenoid change-over) a fraction of a second AFTER you pushed the sound button and you held the sound button in until AFTER you released the footswitch, then you were engaging the solenoid coils while the entire system was muted. Of course this left you with a second or two of a muted soundtrack, not what I would call an elegant solution, but I guess it is much better than the alternative. You hardly notice the "dead air;" but you sure do notice the 85db THUUUUDHUMMMMTHUUUD.

Only thing I think would really work....wrap the damn C/O unit in mumetal (made from cows' hooves).
 

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