|
Author
|
Topic: Variable light output on Elmo ST-1200
|
|
|
Andrew Woodcock
Film God
Posts: 7477
From: Manchester Uk
Registered: Aug 2012
|
posted January 18, 2015 04:54 AM
Where are you getting your new transformer from Winbert with all the right tappings on its secondary winding?
If you just used an external transformer then the switch on the machine would not work for the two lamp settings unless you somehow worked the wiring to a plug in point on the side of the machine, like a Bulgin for example, and then back to the lamp again.
A better, more professional and neater concept, would be to fit a different transformer into the machine itself but then don't forget it has to have the same motor voltage output tappings,the same physical size as the existing one if you want the projector in tact. Then you need an 18v and 24v tapping while maintaining the VA rating of the original one.
As for a dimmer, somehow you would then need to find the room and do a professional cosmetic job of fitting a variac as the output to the lamp is ac not dc so a simple variable resistor is not an option not at least without fitting a bridge rectifier at the lamp output stage of the transformer.
I have to say, without taking into account telecine machines, I don't think I have ever seen a projector with a dimable light circuit. Why would you want to uprate the projector to make it brighter, only to then want to reduce the lamp output with a dimmer switch? To me that does not make any sense and the only reason projectors have a "low" lamp setting is to prolong the lamp life slightly by feeding it fewer volts than it is designed to operate at.
These days the Osram Xenophot range of lamps are so inexpensive for 50 hours of use per lamp, that I never use the low lamp setting as the maximum brightness obtainable from my machines costs me less than a fiver for 50 hours minimum viewing time when the lamps are purchased in packs of ten.
All in all the whole concept ain't gonna be an easy thing to do let alone finding or fitting a correct transformer in a manner that retains the dignity of the machine, I would have thought.
Another point to consider is that if you were to fit a F1.0 lens and a two bladed shutter to your ST1200, you would probably see a brighter on screen image than using the standard lens and 3 bladed shutter with a 250w lamp.
Therefore is it even worth the effort until you already have the maximum brightness from your machine assuming you do not already have this configuration on your ST1200?
[ January 18, 2015, 06:51 AM: Message edited by: Andrew Woodcock ]
--------------------
"C'mon Baggy..Get with the beat"
| IP: Logged
|
|
|
|
|
|
Andrew Woodcock
Film God
Posts: 7477
From: Manchester Uk
Registered: Aug 2012
|
posted January 18, 2015 07:10 AM
Why if your lamp is 15v 150w do you assume it has to be DC Winbert?
The supply comes directly from the secondary windings on the transformer via the switch therefore it is indeed AC as you would find out for yourself if you measured the supply with a voltmeter or multimeter.
Given what you are trying to achieve (creating a dual purpose machine), the easiest way I can think of for you, is to buy something like an old NJD Datamoon and simply route the extended lamp cables in it, out to a second lampholder, then switch lamps to 250w type when showing your films outdoors.
In this country an old Datamoon can be got for as little as around £20 on e bay, usually in poor cosmetic condition for that type of money it has to be said.
It is already designed to take the lamp you desire, has a two setting brightness switch an on/off switch and an internal fan to keep it all cool. All you would need to do is extend the lamp cables and disconnect the supply to the gobo motor in a safe manner, simple as that.
There cannot be an easier or more inexpensive way of achieving what you are after I wouldn't have thought.
Obviously, it even comes with the correct type of lamp holder that you would need for the 250w 24v lamps.
The footprint of the Datamoon would comfortably fit on the lower tier of a standard projector stand and would therefore look quite professional as an uprated power supply for the bigger lamp.
I've just spotted one on UK E Bay for the type of price I said.
The item number is 221661964328 if you are interested.
[ January 20, 2015, 02:37 PM: Message edited by: Andrew Woodcock ]
--------------------
"C'mon Baggy..Get with the beat"
| IP: Logged
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andrew Woodcock
Film God
Posts: 7477
From: Manchester Uk
Registered: Aug 2012
|
posted January 28, 2015 10:20 AM
Leave the diffuser and split glass in Winbert and by all means go ahead with your plans due to your surplus lamp inventory.
However using those lamps, I doubt you will feel you have gained very much at all. If you fitted a two blade shutter and a F1.0 lens, the 15v 150w Osram Xenophot lamp would be brighter and whiter than using your standard configuration with a 200w lamp.
If you have the ordinary f1.3 lens fitted to your ST1200 that it came with as standard, you are already losing loads of light output as well as having to place the projector further away from the screen to get the same sized image, therefore losing even more light to the screen.
Also if the lamps you have, are designed to be used in 16mm projectors, then they will not have the filament orientated correctly for the tiny Super 8mm frame, it just doesnt focus the light output correctly for this frame size.
This in turn, will only add further to your dissapointment after your efforts.
There is no Xenophot available to replace the 200w type. Xenophot lamps give off an extra 20% more light than ordinary lamps, therefore to me, using anything else is a no brainer.
[ January 29, 2015, 08:04 AM: Message edited by: Andrew Woodcock ]
--------------------
"C'mon Baggy..Get with the beat"
| IP: Logged
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
UBBFriend: Email this page to someone!
![[Smile]](smile.gif)
![[Wink]](wink.gif)
Printer-friendly view of this topic
