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Author Topic: Welder's inverters for lamphouses? Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-10-2007 09:00 AM                     A 120 volt DC 5 amp supply with a couple of thousand MF storage. This supply would be fed through a blocking diode to the output terminals. The boost supply should be relay activated to drop out when the low voltage side takes over. This can be done by a current sense arrangement that senses the heavy draw on the output. You would also need to add filtration to the welders supply... Just enough... not too much. Too much and you might exceed the inrush current spec. on the bulb, then short lamp life will ensue. Mark  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 03-10-2007 11:57 AM                     Years ago TECO and some other people where using welding rectifiers with "fair" results. Their boost design was to up the amperage lever to strike and manually lower for operation. The aluminum core of these rectifiers where not truely 100% cycle. The ripple was so awful that the bulbs lasted less than 1000 hours with major deposits on the anode / cathode. One of these conversions caught on fire in Miami. The "designer" who has an electrical engineering degree, mounted the ignitor in a plexiglas case....inside...the lamphouse over the bulb. Millers are another story and with mods very servicable. You can use a smaller welder unit with proper filtration and make a serviceable unit for not too demanding situations. On the German version of Film-tech (www.filmvorfuehrer.de) one tech is showing his filter mod on a small welder unit....ich kann deutshen lesen  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-10-2007 12:21 PM                     Some of the older ORC rectifiers are millers the duty cycle of many smaller welders would be an issue Lee Artoe had an interesting method of killing the boost supply that eprad also used They had a magnetic reed switch mounted to the side of the filter choke that controled a relay on the boost supply when the current flowed through the choke when the lamp lit the mag field opened the reed switch dropping the boost supply  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 03-10-2007 01:03 PM                     I serviced many of those reed switches on Eprad units  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-10-2007 03:26 PM                     quote: Gordon McLeod Lee Artoe had an interesting method of killing the boost supply that eprad also used Lee Artoe also burned down at least one theater with his rectifier design and thats why his company sat intact and in limbo at its Belmont Street address for decades until he died a couple of years back. It was always fun to rummage through his place. There were NASA modified Jet Arcs in the basement used as solor furnaces and Ampex tube amps stacked like Chordwood at the end of a tunnel in the basement. He claimed to be the inventor of Xenon which we all know to be a false statement. He also claimed to be the first to automate a booth... actually Artoemate a booth. There were brand new Ashcraft Core Light lamphouses upstairs last time I was there in the mid to late 90's. He was also a slum landlord and ex-Chicago Bears running back... he went through multiple hip replacements over several decades. He was ALWAYS cranky because his hips bothered him so much ! Lee Artoe Article If you look at the Miller specs they are also not rated for continous duty. The Miller man told me they just use one thats alot larger than is needed. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-10-2007 03:32 PM                     The duty cycle is usually inversley proportonal to the output current  |  IP: Logged Matthew Bailey Master Film Handler Posts: 461 From: Port Arthur,TX Registered: Sep 2000 posted 03-10-2007 08:28 PM                     I'm wondering if you want to use the booth's existng motor-generator to operate a xenon lamp how do you do it? I was in a theatre several years ago that was vacant but stll had power to it. It had three Simplex Aeromatic platters & some Simplex,Century & Brenkert stuff (BX 80 head I believe) stripped,dismantled & lying around the booth,but I believe from the way it looked was the the original motor-generator which I started to my surprise it still had power to it,which was being used to operate one or more xenon lamps. The theatre was taken down for a parking lot.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 03-10-2007 11:57 PM                     Kneisley at one time made a ballast kit so you could use a motor generator set. Lee Artoe....he was a character The last time, in the early 1970's, he took me to O' hare airport in a snow storm and we ran off the road a few times I fixed a load of his lamphouses which had major ventilation problems. I bought a few of his Artoe mation projectors, which where Prevost P-70's, for several special venue jobs.  |  IP: Logged Robert Minichino Master Film Handler Posts: 350 From: Haskell, NJ, USA Registered: Dec 2005 posted 03-11-2007 12:02 AM                        As most MG setups I've seen use ballast resistors to limit the lamp current, if the open-circuit voltage is sufficient you should be able to connect the Xenon lamphouse just like a carbon arc (adjusting the rheostat for the correct running current, etc.). It would certainly be an interesting marriage of old and new.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-11-2007 08:48 AM                     Atlantic Audio Visual ran there first north american xenon systems with zies lamphouses off MG sets Xetron also made a convertor box for MG sets as well  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-11-2007 09:42 AM                        The Memphian Theatre in 1979 (Memphis TN....Elvis' favorite!) had Magnarcs converted with an early Christie conversion. Used a MG with small ballasts. The ballasts looked like very small rectifiers that sat on the floor near the lamphouse; weight: 10 lb or less. Other than no light and high power cost; it seemed to work well enough. Louis  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-11-2007 01:18 PM                     Lamps lasted for ever probably because of the usually 12phase output of many of the big hertners and their high impedance  |  IP: Logged Matthew Taylor Expert Film Handler Posts: 186 From: Essex, UK Registered: Mar 2004 posted 04-29-2007 02:58 PM                     Is there anywhere I can get a schematic of the sort of filter and booster circuit needed for a 1600-2000W inverter? I'm quite capable at putting together circuits but not so good at design, so I could do with some direction.  |  IP: Logged

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