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Author
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Topic: DIY Lamp Project
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Graham Ritchie
Film God
Posts: 4001
From: New Zealand
Registered: Feb 2006
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posted July 30, 2012 11:20 PM
Just finished a "get more light" on the screen project for the old 35mm Ernemann, although the 24volt 300watt was ok I had the chance to see if I can improve on things so gave it a go.
I also got an idea taken from a "Super8Filmaker" March/April 1977 article, about getting more life from your lamp. Although in my case I was hoping to use it, not to run the projector with film on a low setting but to "warm" the lamp before giving it the full 36volts 400watt.... well that was the theory.
I must add, I am not an electrician, so if you see something that ain't quite right please say so.
This "above" is from the magazine, its more suitable for editing, they used a rectifier with a rating of at least 20amps at 200PIV [peak inverse voltage], and a toggle switch of 120volts at 5amps. "Note" I am not sure that a 5amp switch would be high enough, as my working out on, eg 15volts at 150watt would need to be a 10amp switch not 5amps.
Anyway this is what I did...working on a zero budget.
One old speaker box, one 24/36volt transformer rated at around 11amps. Bits of old Bauer 35mm lamp house spares, includng the board, a diode, a home made heat sink, a B/H 16mm double switch which I had to modify the cam with a file and a 240volt 5amp switch which will trip at 6.25amps, as mains safety that also came from old Bauer lamp house bits and bobs.
My idea was to have it so when the lamp is first switched on the 36volts AC is fed only through the diode which in turn retification of the full AC wave to half-wave DC. that in turn will reduce voltage from 36 volts AC, to "hopefully" around 18 volts DC. Switching the B/H switch from low "warm up" to full will disconnect that 18 volts DC...thats why I attacked the cam in the switch with a file to make that work" so the inner part of the double switch will give the lamp the full 36volts AC 400watt. That inner switch itself is a double contact switch rated for 20amps so it should be fine.
One thing is a must is a multi-meter I just could not do without it.
The end result was that it actually works with "low" through the diode and full power ![[Cool]](cool.gif) on the next click.
The extra light is good and was well worth the effort and without zapping myself. ![[Smile]](smile.gif)
Da...Da....
Graham. ![[Roll Eyes]](rolleyes.gif)
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