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Posted by Denis Elwood (Member # 1047) on 02-17-2002, 05:02 AM:
I am looking at the possibility of restoring two 35mm projectors of Australian manufacture, still in the bio box ("booth" in US parlance!).
Two questions:
1. How easy are carbon rods to obtain (especially in OZ)?
2. These projectors have never had rod feed motors fitted. Is this unusual, and wouldn't they be a pain in the bum to operate as such?
Posted by John Anastasio (Member # 607) on 02-17-2002, 07:38 AM:
How old are these machines and who made the lamphouses? There were lots of them made in the early days without automatic feeds.
Posted by Stan Gunn (Member # 554) on 02-17-2002, 10:47 PM:
Dennis
we have no problem with getting rods here.
The lamps are most likely AC arcs it is possable to use dc rods on the AC supply.
They burnt much slower than DC does.
Email me your phone number for further discussion on your wonderful find. 
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KALEE FOREVER. CARBON ARC,THE LIGHT OF THE STARS!
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.SERVICE TO 35 AND 16MM PROJECTION EQUIPMENT.
35MM sprockets made to order.
Posted by Frank Angel (Member # 248) on 02-18-2002, 11:29 AM:
Stan, AC power supply powering the arc for film projection? How can that be? James Bond may have had Pussy Galore, but AC arcs would produce Flicker Galore. No way it could be an AC power supply, unless I am missing something here.
Posted by Mark Gulbrandsen (Member # 72) on 02-18-2002, 01:21 PM:
Frank, Before the high intensity days almost all arcs were AC powered. Since they were still focusing a incandescent gas spot on the aperature it didn't matter and there was no flicker. There were too many limitations with AC though and it cannot do high intensity. Ashcan used to make a special High Intensity Arc Lamp though and it came with a special generator that shot the frequency way up and out of flicker perception.
Mark @ Old GTS
Posted by Richard Fowler (Member # 893) on 02-18-2002, 04:22 PM:
Ashcraft Cybel with the special 96HZ generator....I saw a few in storage in Mexico with some Simplex SP Export projectors.
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com
Posted by Gordon Bachlund (Member # 124) on 02-18-2002, 06:19 PM:
Mark:AC arc lamps were in the minority as they required an m-g set to change the frequency as Richard noted. Richardson wrote about these, rather condescendingly as I recall.
Many elderly follow spots were AC, but nearly all projection lamphouses were DC, from the earliest low intensity lamps with their massive condenser lenses, to the reflector type low intensity lamps of the 1920s, to the later high intensity lamps with which I became familiar in the 1950s.
An interesting anomaly of AC arcs was the sound they made. DC arcs were quiet and even-burning.
Posted by Mark Gulbrandsen (Member # 72) on 02-18-2002, 09:01 PM:
Gordon, I thought all the realy old Powers and Simplex lamphouses were all AC arc???Richard, You're right on the frequency, just looked it up in the Blue Book. An interestng system, but why would the Ashcan clan design something like this?
Mark @ GTS
Posted by Stan Gunn (Member # 554) on 02-18-2002, 11:36 PM:
We in OZ had hundreds of small town cinemas set up in small halls useing AC arcs, there was also a power supply made for just that job.It just pluged into a standard power outlet (we have 240V 50 HZ as our standard supply).There were many C&W portable plants made with AC arcs running at 40 to 50 amps, being a portable supply they were of course called TRANSARCS some cinemas had a TRANSARC under the lamp as an emergancy supply, in case the main DC supply failed, some lamps would run on AC or DC.
There are still some being used on DC lamps,haveing had 4 diodes and a bit of C added, they make a good supply, the larger units able to run at 60 to 80 amps, they also made a good small arc welder.
When running AC 50HZ arcs the projector speed was critical, but running at 25FPS was very common,no strobing and you got to go home a little earlier. 
------------------
KALEE FOREVER. CARBON ARC, THE ONLY LIGHT FOR THE STARS!
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.SERVICE TO 35 AND 16MM PROJECTION EQUIPMENT.
35MM sprockets made to order.
Posted by Eli Blasingame (Member # 1052) on 02-19-2002, 12:13 AM:
Carbon arc, thats a fun time there. up to two years ago we were running 1937'S Peerless light house with a simplex head. i miss running those shows. we still have them and I do play with them when I have the time, keep them oiled. they will run forever.
Posted by Gordon Bachlund (Member # 124) on 02-19-2002, 08:45 AM:
Mark, if a lamphouse uses carbons of the same diameter that burn at the same speed, the lamp is set up for AC operation. If a lamphouse uses a positive carbon that is of larger diameter, and often longer than the smaller diameter negative carbon (which burns slower), the lamp is set up for DC operation. The early Powers and Simplex projectors that I ran into in my youth, which were by then curious antiques, for the most part utilized DC lamphouses, most often fed from motor-generators.
The 96-cycle AC lamps were, for all intents and purposes, a hiccup in the evolution of projector light sources.
When I took my Los Angeles City projectionists license test in the early 1950s, the test consisted of two parts, a written exam and a hands-on skills evaluation, the latter being administered in the elderly nitrate booth of a City Hall auditorium. The lamphouses were so wired that either could, at the examiner's will, be fed DC or AC, and a part of the test was to determine which source was in use, it being understood that these were DC lamps and should not be burned on AC. The lamp on AC sputtered noisily and, of course, produced a strobe effect on the screen, while the lamp on DC burned quietly and produced a steady light. Thanks to having "devoured" Richardson and Cameron in my youth, I had no trouble distinguishing between DC and AC operation, and passed the test the first time around.
Posted by Gordon McLeod (Member # 33) on 02-19-2002, 09:29 AM:
The Ashcraft cyclex was also popular on ships as well
The AC carbons contained different core materials as well that produced a different flame and crater. A short version is still available for the Strong Trouper
Posted by Stephen Jones (Member # 16) on 02-21-2002, 10:37 PM:
I remember useing the Transarc with the old H&B slide projector's (remember those Stan) at a number of theatres I worked at in Tasmania some years ago,never had any flicker problem with them.At one Drive-In I worked at used a H&B slide projector running 120 amps D.C wonder the thing never melted.We used to have a fan mounted on the front to keep the glass slides cool.Steve 
Posted by Richard Fowler (Member # 893) on 02-21-2002, 11:14 PM:
The Cybel used 96HZ to give two pulses per opening of a two bladed shutter or a total of four pulses per film frame to minimize flicker....this of course if the projector and motor did not drift too much 
I converted a few of them to xenon for a customer many years ago.........
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com
Posted by Stan Gunn (Member # 554) on 02-23-2002, 05:38 AM:
Richard.I have never seen a 96 HZ convertor in OZ,all the AC installations that I have seen have used the TRANSARCS.
They used the standard 240V 50HZ single phase supply. 
------------------
KALEE FOREVER. CARBON ARC, THE ONLY LIGHT FOR THE STARS!
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.SERVICE TO 35 AND 16MM PROJECTION EQUIPMENT.
35MM sprockets made to order.
Posted by Don Sneed (Member # 955) on 02-23-2002, 02:45 PM:
I have a question...When I first started as a projectionist in 1970, the booth I operated use a MG system (motor-generator) I always thought this to be DC, was this a DC or AC system ?? I later went to another theatre that use a MG system and a tube rectifier as a back up system that I only has to use once when the brushes went out on the MG....so that theatre had to be DC.....whoaaa weeee, we all learn something new everyday....
Posted by Gordon McLeod (Member # 33) on 02-23-2002, 02:52 PM:
The Hertner and other MG sets were a rotary Ac to DC converter as such your arcs ran on DC
In countries with 50 cycle mains and projecting at 25 fps AC arcs are fine as shutter beat interferance frequencys are not a problem So all that is needed is some sort of current limitig ballast such as a large choke or resistorIn 60 Hz countrys it is necasary to run an AC arc at a multiple of 24 to eliminate a beating flicker (much like the effect of a xenon running with a bad diode) Ashcraft made a special MG set for the Cyclex lamps to generate 96 HZ supply
Posted by Stan Gunn (Member # 554) on 02-23-2002, 10:08 PM:
The transarcs used here were just droopy transformers,a bit like an AC welding supply.
A lot of the early lamps were hand feed, auto feed comeing later,
most of the lamp houses made in OZ were AC or DC kinky A. (edit)We also had many mg sets in service also.
------------------
KALEE FOREVER. CARBON ARC, THE ONLY LIGHT FOR THE STARS!
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.SERVICE TO 35 AND 16MM PROJECTION EQUIPMENT.
35MM sprockets made to order.
Posted by Gordon Bachlund (Member # 124) on 02-24-2002, 10:16 AM:
In all likelihood you were working with DC lamps. I encountered several installations in which the motor-generator set was marginally undersized and a rectifier was added in parallel with the m-g set output. In this way, when both lamps were lighted, as just before a changeover, there was no perceptible loss in screen illumination, as the rectifier was assisting the m-g set in maintaining what was essentially twice the normal lamp current.