Hi Fido,
Ordinarily, light escaping is not the problem, the problem is getting it to go in the right direction in an orderly manner...
Depending on the quality of your setup, you could end up needing sunglasses, or needing a photomultiplier.
It is all down to how well you get the light to enter the hole left by the original lamp module, and onto the actual LCD panels.
Read the original DIY thread for details of the different attempts tried. My guess is that unless you find a reflector similar to Marklar's, or do something really esoteric - like a sealed box with its inside surfaces completely coated with front-surface reflectors except for a very small exit apeture, (not guaranteed to work at all), you will end up with either less light, or lower contrast.
The standard 400 watt bulbs do not emit with a point source, which means that unless you have a really esoteric reflection system, if you want a perfectly collimated beam, you are going to have to loose a lot of light.
Bill.
Ordinarily, light escaping is not the problem, the problem is getting it to go in the right direction in an orderly manner...
Depending on the quality of your setup, you could end up needing sunglasses, or needing a photomultiplier.
It is all down to how well you get the light to enter the hole left by the original lamp module, and onto the actual LCD panels.
Read the original DIY thread for details of the different attempts tried. My guess is that unless you find a reflector similar to Marklar's, or do something really esoteric - like a sealed box with its inside surfaces completely coated with front-surface reflectors except for a very small exit apeture, (not guaranteed to work at all), you will end up with either less light, or lower contrast.
The standard 400 watt bulbs do not emit with a point source, which means that unless you have a really esoteric reflection system, if you want a perfectly collimated beam, you are going to have to loose a lot of light.
Bill.
would using a parabolic reflector like those in original lamps make the light source go in uniform manner ?
fido
fido
Fido,
Though the MH bulbs are more efficient, the higher power the bulb, the more heat it generates - both to touch, and in the form of IR light that transmits the heat to whatever absorbs it.
Lumen ratings are a guide to perceived brightness.
With a pure point source of light, a parabolic reflector will generate a parallel beam of light if the light source is placed at its focal point. The bigger MH lighting bulbs are not point sources of light, and are probably too bulky to get the brightest point of their emitting volume close to the focal point of any reasonably sized parabolic dishes. Even if you could, the output would contain a combination of parallel, diverging and converging rays. If your projector needed parallel rays, then you would need to focus this beam through a diaphragm that could be used to mask off the rays that do not follow the path - causing a loss in light output. This might not be the case, and you might get away with something simple...
Other than Marklar's awesome beast, most reflectors built by the DIY gurus for these bulbs are similar in configuration to the rectangular reflectors used in the external halogen/MV/MH/PS work-lights you can buy at DIY places.
Building the precision ortho-parabolic reflectors needed to make the most out of these bulbs is not the strongest skill of the DIYers here, and so far, a lot of light is being lost...
This is why I suggested the (physically) smaller bulbs designed for other things - they may be more expensive with shorter lives than the bigger MH bulbs, but they are much more usable, and still much cheaper to replace than the official projector bulbs. Also, dependant on the percentage of usable light from these things, you might be able to get a brighter, clearer image from these lower powered bulbs...
Bill.
Though the MH bulbs are more efficient, the higher power the bulb, the more heat it generates - both to touch, and in the form of IR light that transmits the heat to whatever absorbs it.
Lumen ratings are a guide to perceived brightness.
With a pure point source of light, a parabolic reflector will generate a parallel beam of light if the light source is placed at its focal point. The bigger MH lighting bulbs are not point sources of light, and are probably too bulky to get the brightest point of their emitting volume close to the focal point of any reasonably sized parabolic dishes. Even if you could, the output would contain a combination of parallel, diverging and converging rays. If your projector needed parallel rays, then you would need to focus this beam through a diaphragm that could be used to mask off the rays that do not follow the path - causing a loss in light output. This might not be the case, and you might get away with something simple...
Other than Marklar's awesome beast, most reflectors built by the DIY gurus for these bulbs are similar in configuration to the rectangular reflectors used in the external halogen/MV/MH/PS work-lights you can buy at DIY places.
Building the precision ortho-parabolic reflectors needed to make the most out of these bulbs is not the strongest skill of the DIYers here, and so far, a lot of light is being lost...
This is why I suggested the (physically) smaller bulbs designed for other things - they may be more expensive with shorter lives than the bigger MH bulbs, but they are much more usable, and still much cheaper to replace than the official projector bulbs. Also, dependant on the percentage of usable light from these things, you might be able to get a brighter, clearer image from these lower powered bulbs...
Bill.
Fido,
making this external lightsource depends of the size of the lamp, which you should get in to a parabolic reflector. Remember, the lightsource has to be at the focal point of the reflector to get a parallel beam out of it. The aperture of the reflector should of course not extend the size of original lamp. This could be a mechanical problem, to get the lightpoint at the focal point of such a small reflector.
BTW, do you notice any life on LCDpanel without a lamp?
xblocker
making this external lightsource depends of the size of the lamp, which you should get in to a parabolic reflector. Remember, the lightsource has to be at the focal point of the reflector to get a parallel beam out of it. The aperture of the reflector should of course not extend the size of original lamp. This could be a mechanical problem, to get the lightpoint at the focal point of such a small reflector.
BTW, do you notice any life on LCDpanel without a lamp?
xblocker
i dont understand life on lcd panel without a lamp ?
I may just sell it as there is 1800 hours lamp life left and i cant really afford the upkeep of these things
fido
I may just sell it as there is 1800 hours lamp life left and i cant really afford the upkeep of these things
fido
fido,
sorry, it was the question, that woneill already asked, did you see the LCDs working without a lamp?
xblocker
sorry, it was the question, that woneill already asked, did you see the LCDs working without a lamp?
xblocker
Now i have to design something for this
Now i have another dead projector to design stuff for.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1364794572
Its native svga so thats a plus.....now to get the focal length and right type of light......any thoughts
Before I go off the deep end witch project should i work on first
1) 3 panel Proxima DP5100 with canabalized lamp...uses evd bulbs...dimmer than the 250 watt MH that was there
Specs: 640*480 3 panel lcd with 200:1 contrast ratio 16.7m colors, power zoom lens
2)Infocus LightPro 220
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1364794572
Missing bulb and lens assebmly
Specs: 800*600 native....interpolation to 1024*768, 200:1 contrast ratio.
I currently have a 3M 9550 OHP with an infocus TVT3000 LCD 640*480 res that I'm using.......
3) Upgrade LCD panel to a 1024*768 panel. (still have to purchase)
Whats the best option for me guys......wich PJ should i start working on first?
I dont plan on using the correct bulb in any situation...will be a custom job, and i will source a lens from somewhere for the infocus. Where should I spend my time/efforts/money on first
Now i have another dead projector to design stuff for.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1364794572
Its native svga so thats a plus.....now to get the focal length and right type of light......any thoughts
Before I go off the deep end witch project should i work on first
1) 3 panel Proxima DP5100 with canabalized lamp...uses evd bulbs...dimmer than the 250 watt MH that was there
Specs: 640*480 3 panel lcd with 200:1 contrast ratio 16.7m colors, power zoom lens
2)Infocus LightPro 220
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1364794572
Missing bulb and lens assebmly
Specs: 800*600 native....interpolation to 1024*768, 200:1 contrast ratio.
I currently have a 3M 9550 OHP with an infocus TVT3000 LCD 640*480 res that I'm using.......
3) Upgrade LCD panel to a 1024*768 panel. (still have to purchase)
Whats the best option for me guys......wich PJ should i start working on first?
I dont plan on using the correct bulb in any situation...will be a custom job, and i will source a lens from somewhere for the infocus. Where should I spend my time/efforts/money on first
eebasist,
Wow, sounds like fun!
I would go after the latest one - just to see if a fix is feasible and to see if you can learn something new.
You might find something in the one you know least about that could change your approach on the other ones you have been working with. e.g. As a result of receiving a couple of projector beam fog lamps yeaterday, I am now currently experimenting with the use of prisms to merge two beams of collimated light into one.
If I can produce something useful, we might be able to get around some of the limitations and lost light resulting from the large size of the big MH bulbs. Then again, we might not...
All learning is good learning! Enjoy!!!
Bill.
Wow, sounds like fun!
I would go after the latest one - just to see if a fix is feasible and to see if you can learn something new.
You might find something in the one you know least about that could change your approach on the other ones you have been working with. e.g. As a result of receiving a couple of projector beam fog lamps yeaterday, I am now currently experimenting with the use of prisms to merge two beams of collimated light into one.
If I can produce something useful, we might be able to get around some of the limitations and lost light resulting from the large size of the big MH bulbs. Then again, we might not...
All learning is good learning! Enjoy!!!
Bill.
Work on the SVGA model.
I assume the bulb is dead and you are not going to locate a new one and you will no be able to locate a small enough bulb to fit in situ so pull the bulb, reflector and ballast taking great care with the bulb that it does not explode. Face mask and heavy duty leather clothing and gloves is a must. Its very unlikely a cold bulb will explode but dont touch the bulb and dont take any chances. They are under pressure even when cold. The bulb and reflector assembly is probably in a metal enclosure.
There should be a mechanism that tells the projector if the bulb is lit or not . You will need to work out a bypass. Often its just a light activated device like an LDR. Sometimes its a switch contact that only determines if a bulb is in place.
You either have an elliptical reflector or a parallel reflector. either one is based on a point source bulb which you will find expensive so you need an alternative. Most likely it will be a parallel reflector. You might be able to find a larger bulb that will fit inside the reflector. Careful with the original bare bulb.
Initially a car headlamp through a 2 inch hole should give you a rough parallel beam, aim it into the projector where the original light path was and in darkness with luck you can see the white light going to the 1st beam splitter and coming out red blue and green.
When you have finished experimenting cover the unit to keep out dust and dont be tempted to touch any of the adjustment screws.
Overall you will have some difficulty getting a parallel beam of sufficient strenght as original so you will have to use something like a 400 watt metal halide and waste some light to get it going.
Not a bad tradeoff and a lot of fun.
Good luck
I assume the bulb is dead and you are not going to locate a new one and you will no be able to locate a small enough bulb to fit in situ so pull the bulb, reflector and ballast taking great care with the bulb that it does not explode. Face mask and heavy duty leather clothing and gloves is a must. Its very unlikely a cold bulb will explode but dont touch the bulb and dont take any chances. They are under pressure even when cold. The bulb and reflector assembly is probably in a metal enclosure.
There should be a mechanism that tells the projector if the bulb is lit or not . You will need to work out a bypass. Often its just a light activated device like an LDR. Sometimes its a switch contact that only determines if a bulb is in place.
You either have an elliptical reflector or a parallel reflector. either one is based on a point source bulb which you will find expensive so you need an alternative. Most likely it will be a parallel reflector. You might be able to find a larger bulb that will fit inside the reflector. Careful with the original bare bulb.
Initially a car headlamp through a 2 inch hole should give you a rough parallel beam, aim it into the projector where the original light path was and in darkness with luck you can see the white light going to the 1st beam splitter and coming out red blue and green.
When you have finished experimenting cover the unit to keep out dust and dont be tempted to touch any of the adjustment screws.
Overall you will have some difficulty getting a parallel beam of sufficient strenght as original so you will have to use something like a 400 watt metal halide and waste some light to get it going.
Not a bad tradeoff and a lot of fun.
Good luck
you say put a larger bulb into the reflector😕 how can you put a 400 watt metal halide bulb in there ?
what is an ldr ? and where would it be located ?
fido
what is an ldr ? and where would it be located ?
fido
Fido,
in a german HT-forum i have read from a guy, who replaced the original 400w MH lamp with a 250w halogen from a slide projector.
He used the original parabolic reflector and fiddled the socket of the halogen lamp at the reflector. He couldn't bypass the power modul, so he used the complete power section of the slide projector.
The results seem to be good, image is little more reddish, but usable, as he said.
xblocker
in a german HT-forum i have read from a guy, who replaced the original 400w MH lamp with a 250w halogen from a slide projector.
He used the original parabolic reflector and fiddled the socket of the halogen lamp at the reflector. He couldn't bypass the power modul, so he used the complete power section of the slide projector.
The results seem to be good, image is little more reddish, but usable, as he said.
xblocker
sounds interesting xblocker, so is it possible for me to put in a metal halide bulb with same rating even if i have to fiddle the lamp terminals etc as long as it sits into the lamp module and doesnt petrude out it has a good chance of working ? i have found some metal halide bulbs with same wattage as mine and would be small enough to fit in my projector lamp unit if i modified them slightly would it be pssible to try these as i would assume the worst would be a blown lamp/fuse. also is it bulb wattage or lumen rating that makes them hotter ? and does it matter about the polarity of these bulbs ? i am wanting to find out what voltage my lamps starts at and runs at.... is there any safe way of achieving this without danger of electric shock i guess the start voltage would be way to high to test with a domestic multimeter.
these lamps are very cheap and are rated the same wattage as my original they are also igniter started
or maybe these could be modified also same rating
fido
these lamps are very cheap and are rated the same wattage as my original they are also igniter started
An externally hosted image should be here but it was not working when we last tested it.
or maybe these could be modified also same rating
An externally hosted image should be here but it was not working when we last tested it.
fido
It may depend of the lamp design to get it into the reflector. If you get the lightpoint at the focus point it should work, but the lamps design should not conflict with the light path. perhaps you should use an additional safety glass between the lamp and the rest(including yourself). And, yes, lamps wattage corresponds with heat. So a 120 UHP lamp is brighter and generates much less heat than a 400w conventional MH lamp. It's the lumen/wattage ratio, which dramatically increase with new technologies, as $$$ increase.
MHs are driven by AC or DC, and as far as i know DC powered lamps should last longer. In every case starting voltage is very high (dangerous!) and should not checked out without basic knowledge and knowing of specifications.
xblocker
MHs are driven by AC or DC, and as far as i know DC powered lamps should last longer. In every case starting voltage is very high (dangerous!) and should not checked out without basic knowledge and knowing of specifications.
xblocker
so although the above lamps are much higher in lumen than my original it shouldnt burn anything out considering they are the same wattage ? so how would the extra lumen in these bulbs affect my projector ?
fido
fido
aren,t lumen and ansi the same ?
but what about the much higher lumen will this make my projector better or worse ?
but what about the much higher lumen will this make my projector better or worse ?
NO,NO,NO!!
Very short: Lumen is the overall brightness of a lamp, ANSI lumen is a measure, defined by SMPTE society to judge projector's brightness on a screen. A screen is diveded by 9 symmetrical parts and each part's brightness is measured. The medium value gives ANSI lumens! The lamps lumen value is of course much more than ANSI can be due to light loss and absorbation.
xblocker
Very short: Lumen is the overall brightness of a lamp, ANSI lumen is a measure, defined by SMPTE society to judge projector's brightness on a screen. A screen is diveded by 9 symmetrical parts and each part's brightness is measured. The medium value gives ANSI lumens! The lamps lumen value is of course much more than ANSI can be due to light loss and absorbation.
xblocker
Fido,
When you say you would modify the bulbs slightly, what exactly do you mean?
If you are thinking of physically altering them in any way, especially the glass bit, be VERY careful - they are highly pressurised and can explode.
As for running equivalent wattage bulbs with your original ballast, I would listen to Xblockers suggestion about the extra safety glass.
Even if the power ratings are the same, the bulb could be expecting a very different drive signal from the one produced by the ballast. If they are too mismatched, then one or other could smoke, or blow up. Fuses don't always work, especially when connected to the input to the ballast - it might draw the same power, but could still be operating way outside of its safe zone.
Keep a fire extinguisher handy, just in case.
Bill. 😱
When you say you would modify the bulbs slightly, what exactly do you mean?
If you are thinking of physically altering them in any way, especially the glass bit, be VERY careful - they are highly pressurised and can explode.
As for running equivalent wattage bulbs with your original ballast, I would listen to Xblockers suggestion about the extra safety glass.
Even if the power ratings are the same, the bulb could be expecting a very different drive signal from the one produced by the ballast. If they are too mismatched, then one or other could smoke, or blow up. Fuses don't always work, especially when connected to the input to the ballast - it might draw the same power, but could still be operating way outside of its safe zone.
Keep a fire extinguisher handy, just in case.
Bill. 😱
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