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GS1200..250Watt lamp

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  • #16
    The reflector looks similar to the type used for GU10 12v 50W long life lamps for display lighting.


    • #17
      Just another thought if you don't want to pull some old slide projector apart, then this type of sealed external unit transformer might be the thing. I bought this one new many moons ago for the Ernemann 2, to supply a 24v 300watt lamp. In time I replaced it, with a now, 36v 400watt power supply for the Ernie.

      You can buy such sealed transformers such as this from certain electrical suppliers. This one unit alone is rated for 24v 350watt output, so there is more than enough for a 24v 250watt lamp. These sealed units are fused for safety.
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      • #18
        Having trouble finding a source for a 24v 250 watt power transformer to run the ELC lamp. I found this one which supplies DC for LED lighting. Would this work?


        • #19
          Hello to all!
          The new produced OSRAM 250W ELC Cold Mirror Halogen Lamps I had bought had a very dull Light output and a short Lifetime. The Quality is not the same as they had back in the 90´s. And this Lamps are focused for the 16mm Image and not for the Super8 Image. The Lightbeam ist to large for this little Frame. So I have done it another Way. Cut of a Philips Mirror from a 250W ELC Lamp and stuck in the OSRAM Two base Pin Lamp 24V 250W. So now I can focus the Filament forwards and backwards in the Mirror to concentrate the optimal Light Beam onto the small Super 8 Frame. For the Power Source I´m using a 400W 25V external Transformer. I drive this Lamps with 25,2 V and get a Lifetime of 45h. The Lightoutput is amazing and the Prize for one Lamp is only 1,15 Euro.


          • #20
            Hi Thomas

            I had been working on a similar project, thanks to your idea mentioned a while ago. The hardest thing was making the hole without damaging the reflective part of the mirror. Even though I used masking tape to protect it, I had to be really careful.

            Its a on going project at the moment, I am on two minds, one to use the 24v 250watt or the 24v 300watt lamps which I have a few of. The hole is big enough, to allow either lamp to slide forward or back through the mirror as I adjust the focus with the projector running in Scope. The bracket will still be 10mm back, as you suggested a while back. It will be interesting to see how much more light, well hopefully, the fact of being able to focus the light better on the gate.

            All those parts shown here are spares than I am working with.
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            Just getting the hole right using a old faulty lamp.
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            • #21
              Good work there. I remember reading of how Keith Wilton had to modify the reflector in his Chinese 35mm projector to take a different type of Xenon lamp and the trouble he had getting the position right after. A long, tough job but well worth it in the end.


              • #22
                Finished working on it today, but that's it until after Christmas as I hope to run some Super 8 films with the present lamp set up, I will try it out later on the GS1200. It will be interesting to see how it works out. The lamp alignment to the mirror will be carried out with the projector running and cooling. Its just a matter of sliding the lamp either fwd or back through the mirror, to get a even and bright light from the EHJ 24V 250W lamp.

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                • #23
                  Very nice job Graham


                  • #24
                    Thanks Lee

                    Its great what you can do with bits and bobs however the proof of the pudding is trying it as they say. A good indicator will be running the projector in very short bursts with the Scope lens in place "no film". If I can adjust the lamp to get more light through that Scope lens that would be real plus.

                    PS. Its thanks to Thomas on the forum that gave me the idea in the first place


                    • #25
                      Hi Graham!
                      It is a pleasure for me that you try to do it again. I have made this Conversion in 2018 and i have it now in all of my four machines. I run this EJL Lamps with 25,2V and they bring a Lifetime of 45 Hrs.


                      • #26
                        I had been meaning to get back to Thomas regarding this conversion, as he had just mentioned it on another post I thought I better reply now. It did work on the GS1200 but I did notice the lamp house getting a lot warmer than usual. The conclusion was I did not see any advantage light wise over the present arrangement using the Osram ELC 24v 250w lamp. Thomas you did mention increasing the speed of the cooling fan that would take of the cooling, but I again decided to return to the ELC.

                        I feel the present arrangement that you came up with, mounting the ELC lamp 10mm back is the best for me. Thomas you were spot on with the 10mm back as the light output is better focused

                        The combination of the Osram Xenophot 64653 HLX ELC being mounted back and the two bladed shutter I made and fitted to the GS1200 a while back, will do for the time being

                        I have that mirror, the one with the hole in it and all the bits to go with it carefully put aside so I might return one day and give things another go one thing though can you get a 24v 250w lamp that can go through the mirror, that has a straight up and down "vertical" internal filament, would that work better?

                        Thomas I came across this particular article in a old magazine that might interest you.....

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                        Last edited by Graham Ritchie; May 06, 2021, 02:05 PM.


                        • #27
                          I'd say the coating wasn't dichroic (as that would change the colour) but diathermic. I'm sure magazines called it that in later years.


                          • #28
                            Yes, I have tried this too & I found that with the Osram 24V 250W capsual lamp, the filament is orientated wrong, I could not get a very bright picture compaired to the ELC.


                            • #29
                              The 250 watt lamp was designed primarily for to illuminate the larger 16mm frame. When this lamp is used for the 8mm frame the larger spill of light is mostly focused away from the gate aperture. Because of this there is very little improvement in lux output. What is increased is the extra amount of heat that is generated from the 250watt lamp that the elmo GS1200 fan was not designed to cope with.


                              • #30
                                Hello at all!
                                I have used the 250W ELC over many Years in my GS 1200 in the same Way that Graham told. But this Lamp of today is not the same as you could buy in the 80´s or 90´s. They have another Glue in use for holding the Bulb inside the Mirror with the Result of getting black Dots on the Bulb and they are bad focused in the Mirror. Today I use the Base Pin Lamp 250W/24V like it was in many Slide Projektors in use. This is the best Halogen Lamp for the GS ever. But you have to drive it with an external Transformer, like Graham did with the ELC. And the Fan Motor must be swiched to the Amplifier Coil of the Elmo Transformer with an extra Cap and Rectifier because the Main Motor and the Fan Motor are on the same Rectifier and when both are running the Voltage drops down to 35V. But if you swich it to the Amplifier Coil you have 40-41V on the Fan Motor and the Cooling is much better now. And you need a Shield of thin Aluminium over the Lamp holder inside the Lamp House for concentrate the Airflow to the Lamp. I have made a few Photos of the Air shield The Conector Box on the Top for conecting the external Transformer and the little Board with Rectifier and Cap for the Fan Motor. The little Relay i have thrown away from this Board now. I a swich tis now by Hand with the little Swich in the conector Box on the top. Everything on the Projector is original working. The Lamp Swich low and high. The Fan Motor is going to high when swich on the Light. And when the Machine is running you can swich on the boost for the Fan Motor. This is working very well only in Summer when it is very warm over 30 Degrees than it is to hot for the Elmo GS 1200.