Film-Tech Forum ARCHIVE: Rectifier information needed

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Posted by Bill Mantz (Member # 754) on 08-25-2003, 03:50 AM:

I have a Christie K20 lamphouse and will be using 1K bulb. I have a Kneisley Kni-Tron rectifier Model R-2180-4 input is a single phase 115 volts output 18 volts DC at 30 amps. Dose any one have a manual or any other information on this rectifier. I also have a LP Associates 8501 rectifier which rectifier would be the best one two use.
Thanks

[ 08-25-2003, 06:17 AM: Message edited by: Bill Mantz ]

Posted by Jack Ondracek (Member # 1466) on 08-25-2003, 05:02 AM:

Bill, I don't know the supply, but I'm going to take a wild stab at this & say that I don't think it will work for you. That looks suspiciously like a carbon arc supply. If so, it won't provide the no-load voltage you'll need to ignite a xenon lamp.

Then there's the face plate info you posted. 18 volts at 30 amps rates the supply at 540 watts, full out. Even if it has the filtering required for a xenon lamp, and if you can get the no-load volts out of it (which I doubt), it won't give you enough amperage to handle your 1kW bulb.

That old asbestos covered wire is just about a dead giveaway, too, since that stuff was so popular during the arc days.

Hope I don't wind up with egg on da face, but I think you'll be looking for another supply for this application.

Posted by Daryl C. W. O'Shea (Member # 1303) on 08-25-2003, 05:19 AM:

Yup, it's a carbon arc rectifier. You could use it in conjunction with a Kniesly Konversion to operate a small xenon lamp, but you wouldn't have enough current to run your 1kw lamp.

Posted by Richard Fowler (Member # 893) on 08-25-2003, 06:37 AM:

The Kneisley is a 500 watt xenon model for a lamphouse that they made for small screening rooms and for 16/35mm projectors.When they first made the product 30 years ago asbestos cable was still an option. 18 volt / 30 amp is for xenon, carbon arc runs at a higher voltage. The Kneisley is also very ( old design ) inefficient requiring a bit of A.C. power to give you the 500 watts. The LP 8501 is the best match.

Posted by Tim Reed (Member # 137) on 08-25-2003, 07:37 AM:

FWIW, most older Kneisleys look like carbon arc supplies.
[Big Grin]

Posted by Adam Fraser (Member # 1074) on 08-25-2003, 10:01 AM:

Bill, I believe we have the exact same rectifier for our 500w spotlight that we bought from kniesley. I may be able to copy some pages if I can find the manual. But sure looks exactly like our spotlight supply.

Posted by Jack Ondracek (Member # 1466) on 08-25-2003, 11:14 AM:

OK... I'll take Half an egg...

...it LOOKS like a carbon arc supply! [Big Grin]

Posted by Daryl C. W. O'Shea (Member # 1303) on 08-25-2003, 01:52 PM:

Ditto! It looks like a carbon arc supply. [Smile]

I guess never having run carbons on such a 'small' power supply I would have clued in. Who whoulda thunk!

Posted by Michael Schaffer (Member # 1204) on 08-25-2003, 05:08 PM:

Question: I notice it says Toledo, Ohio on the plaquette. That is where Strong was located before moving to Nebraska. Is there a connection between Strong and Kneisley?

Posted by Tim Reed (Member # 137) on 08-25-2003, 05:36 PM:

Not to my knowledge. Strong just happened to be in Toledo before Ballantyne bought them.

Posted by Richard Fowler (Member # 893) on 08-25-2003, 05:46 PM:

Dick Kneisley worked for Strong in the 1930's and later started his company making high intensity carbon arc kits to replace low intensity units. He lived to see his 90's. Dick retired to Florida. Kneisley also makes equipment for the graphics art industry.

Posted by Bill Mantz (Member # 754) on 08-25-2003, 11:47 PM:

Thank for the information. Now a new question who makes small 500 Watt lamphouses that I could retrofit a 16mm or a 8mm projector to get more light on the screen.

Posted by William H. Ward (Member # 1797) on 08-26-2003, 08:43 AM:

Hi... Let me add this.... I remember a 30 amp 28vdc rectifier made for carbon-arcs for the Strong Jr. Hi lamps for 16mm use. It kinda looked like the one in the photo. The lamp burned the Pearlex trim (6mm pos x 5.5mm neg) at 30 amps. I also knew Kniesly built a rectifier for a 500w xenon and looked similar, but it had no asbestos leads. Its open circuit voltage was 70vdc and load was 16-21 volts at 28-30 amps. Its output was filtered by a set of capacitors and 2 chokes. Extensive filtering of dc for xenon bulbs is a has to be. Carbon-arc supplies do not have a requirement for as much smoothing. Check ou your unit to see if it has the extensive filtering.