Film-Tech Forum ARCHIVE: Tungar tubes

This is topic Tungar tubes in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=005995

Posted by Jim Spohn (Member # 1547) on 03-25-2004, 02:41 PM:

Can anyone tell me how to substitute diodes for tungar tubes? They are used as a pair in my 16mm projector rectifier. These tubes have three connections. One on the base tip --one on the screw base shell and then the plate connection on top. Thanks for any help....Jim

Posted by Jeff Taylor (Member # 443) on 03-25-2004, 02:46 PM:

check out www.widescreenmuseum.com/sound/rca05-06.htm. It has a simple layout for a tungar rectifier you should be able to adapt from.

Posted by Scott Norwood (Member # 30) on 03-25-2004, 02:48 PM:

Are tungar tubes the same thing as sil-tubes? The ones I'm familiar with look like metal soup cans with mogul or Edison lightbulb bases. I've also seen "rectifier tubes" which look like giant lightbulbs. I assume that these are something different entirely?

Posted by Jeff Taylor (Member # 443) on 03-25-2004, 02:51 PM:

The tungars are the ones that look like giant light bulbs, Scott.

Posted by Jim Spohn (Member # 1547) on 03-25-2004, 03:05 PM:

Thanks, Jeff thats just what I was looking for.
Scott, your right on the money, they have mogul base sockets and a connection on the top for the plate. Thanks again...Jim

Posted by Jeff Taylor (Member # 443) on 03-25-2004, 03:10 PM:

appropos of nothing, but when I was in Jr. High in the late '50's we had a carbon follow spot that had a tungar rectifier. Damn thing looked like someting out of a Flash Gordon set.

Posted by Jon Miller (Member # 163) on 03-25-2004, 08:38 PM:

Here's one of a quartet of solid-state Tungar bulb replacements I made about a decade ago for a Strong-built National Theatre Supply "intermediate four-tube" carbon arc rectifier...

I used DSI75-12B diodes, rated at 110A at 1200V (seriously overrated, yes, but very able to handle the current surge of striking an arc). The diode and heatsink are mounted to a pair of brass L-brackets, which I attached to a five-inch length of 1-1/2" diameter type "L" copper pipe using brass screws. The mogul screw bases came from burned-out sodium-vapor street-light bulbs. I soldered a pigtail to the diode's tip for something to attach the large Fahnestock clips to and to keep the clips spaced safely away from the heatsinks. The electrical connection at the screw base is through the shell only; since there is no need to heat a filament, the tip connection is moot.

What can I say? They're ugly, but they work. I gained about five extra amperes of available current from the rectifier in switching from Tungars to these contraptions. [thumbsup]

Posted by Steve Kraus (Member # 476) on 03-25-2004, 08:46 PM:

That's a great idea.

Here is a 2-tube Tungar rectifier I have for a baby arc lamp:
http://steve.filmteknik.com/tungar.html

Posted by Tim Reed (Member # 137) on 03-25-2004, 09:22 PM:

Don't forget to lower the input power to the unit(s) as you will gain the voltage drop that was formerly across the filaments of the Tungar bulbs.

Posted by Jim Spohn (Member # 1547) on 03-26-2004, 09:50 AM:

Thanks Jon, what a nice replacement unit you built. I'm going to fashion my units very much like yours thanks to your inspiration.
Steve...I have two rectifiers just like yours. The lamps were built by Strong. They look just like a magna-arc except they are 17" long and 10" in diameter, they're ultra cute. The lamp may be seen in the Film-tech manuals under Strong Low Intensity lamp. By changing the the shunt for the motor, you can burn 7mm and 8mm copper jacket carbons and get a heck of a bright light for 16 or 35mm projectors. Thanks Guys for all your help.....Jim

Posted by Ken Layton (Member # 133) on 03-26-2004, 10:10 AM:

A sil tube is the solid state replacement for a tungar tube.

Posted by Rick Long (Member # 213) on 03-26-2004, 11:07 PM:

Kneisley R-1160 as I recall.