Amplifier from projector

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gary o

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Dec 28, 2004
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Found an old projector in a shed int he woods... GB Equipments, british acoustic films ltd London .... I cant find info or pictures or schematics of it on line, its in terrible state but I think I can get the mechanics to work & fashion some lamps to project, it has two films...I been reading how the optical sound works facinating ....

Questions are....Does anyone know  where I can find a schematic....

Can I somehow connect to modern amplifier from LDR to hear to sound, maybe rebuild input part of its amp

Or maybe I can use its transformers & tubes for mic pre or vari mu compressor, maybe LDR and light system can be used to mess with some audio in a good way




 

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My buddy takes bell and Howell projectors and guts the tube amps making them into guitar amps.  They sound good. I am sure you can do similar with minimal effort.
 
The valves (tubes) in that thing are old!
If you don't have them and working I doubt you'll be able to find them now....
 
gary o said:
British acoustic films ltd London .... I cant find info or pictures or schematics of it on line, its in terrible state but I think I can get the mechanics to work & fashion some lamps to project, it has two films...I been reading how the optical sound works facinating ....

There's a pdf of a US patent here:

http://www.freepatentsonline.com/2191795.pdf

Has some basic schematics.

Love that you're going to try and restore this projector. Too many of them are being gutted for parts, or scrapped. We've been having some problems in getting a projector for some historical movies we wanted to show. We have a 35 mm one that has been restored, but the other formats can be a pita.

Can I somehow connect to modern amplifier from LDR to hear to sound, maybe rebuild input part of its amp

Are you sure it's an LDR?

In the schematic in the patent opto-tubes are used.
 
The sound-head will be a photo-tube. It needs a teeny amount of 90+ Volts, cap-coupled to a very high input impedance (guitar amp).

Those tubes are early-mid 1930s. The build may be some newer, but sitting "in a shed int he woods" I would really doubt enough works to be worthwhile. Damp gets in transformers and capacitors, breaks-down the insulation; older resistors also got damp-rot. That broken power tube is now rare and seems to sell for $900 when one comes to market.

The films: you can know what they are by spooling off a few feet and reading the title with a magnifier. If it looks like pre-war pornography you can spool the whole thing and linger over the exciting scenes. If it is 16mm wide, EVERY school and library used to have a 16mm projector. Call around and find some place which hasn't yet thrown theirs in the rubbish.
 
If it looks like pre-war pornography you can spool the whole thing and linger over the exciting scenes.
Why else would someone have a projector in the woods?!? ::)

DaveP
 
Wow thanks for the responses ;) chaps & thanks for patent Cyrano  :)....yes wasn't going to restore, sadly the thing as PRR says its rotten as hell from damp....the mechanics are ok so i was asking how to connect sound head ( what I had read as LDR) to a modern amp & maybe use input components of its own  self if needed,,,so plan was to use mechanics & project the films I have (sadly not 1930s porn haha) just for fun really ...I know i can scan the frames with me DSLR stick em thru a program...so just for the hell of it... & wanted to hear how bad the optical sound will be & learn about that too

So is photo tube like LDR ??

Very interested in limiters can I use photo tube in LA2A again for fun

DIY ed a BA6A about 15 years ago & been in love with vari mu ever since tried many circuits over the years wondered if I can use Parts for old vari mu ...anyway its not going to waste either way... yes was in a chaps shed he lived in the woods for over 40 years no electric gas or anything...he  was a hoarder of electrical stuff he couldn't even use poor old sod
 
http://www.cinerdistan.com/Pictures%204/Ampro%20Amp%203a.jpg

Aha  similar machine i guess

Off to experiment thanks for info
 

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