NordicNINE,
Don't know about Home Depot - check out their website. (I would myself, but for some reason, their site sux. I have not seen a site this bad since the mid 90's...)
There are plenty of sites on the web selling such things.
Once you have your floodzilla, how are you intending to use it? As-is? In an OHP? Ripped appart? In a new projector design?
Bill.
Don't know about Home Depot - check out their website. (I would myself, but for some reason, their site sux. I have not seen a site this bad since the mid 90's...)
There are plenty of sites on the web selling such things.
Once you have your floodzilla, how are you intending to use it? As-is? In an OHP? Ripped appart? In a new projector design?
Bill.
I've checked out their site a couple times over the last week and it does suck. Searches don't find everything well. It's really slow, etc...
I'll just swing by tomorrow.
I might rip out the guts of the OHP and modify the back of the projector to have the flood (or whatever I use) to shine in and get reflected up using a mirror if I can get the right angle, but since I'd want to make a cover or something to prevent light from shining on ceiling, I'll probably just make a whole enclosure.
I'll just swing by tomorrow.
I might rip out the guts of the OHP and modify the back of the projector to have the flood (or whatever I use) to shine in and get reflected up using a mirror if I can get the right angle, but since I'd want to make a cover or something to prevent light from shining on ceiling, I'll probably just make a whole enclosure.
NordicNINE,
There might be a little more to it than you are thinking.
Check out the main thread for more info: the OHP fresnels are expecting a point source. Your floodzilla will be trying to give out a "flood" style beam...
Much of the work in the forums has surrounded trying to get the perfect light source/reflector combination. Before you commit to anything, see which approach appeals best.
There is not yet a single answer...
Bill.
There might be a little more to it than you are thinking.
Check out the main thread for more info: the OHP fresnels are expecting a point source. Your floodzilla will be trying to give out a "flood" style beam...
Much of the work in the forums has surrounded trying to get the perfect light source/reflector combination. Before you commit to anything, see which approach appeals best.
There is not yet a single answer...
Bill.
The existing reflector in the OHP, doesn't just reflect the light. It's spreading out the point source, true?
I have a couple other things in mind, it case it's not as easy as I think. 🙂
I have a couple other things in mind, it case it's not as easy as I think. 🙂
It depends which reflector you mean: my OHP uses FXL bulbs that have their own reflector, but it still uses a mirror to deflect the path of the light beam towards the fresnel.
Other OHPs use a naked bulb, but mounted inside a reflector built in to the OHP. This reflector is designed to beam the maximum amount of light from the bulb towards the fresnel.
Either way, the fresnel is expecting to see a single point source of light - the reflectors are there to gather the maximum amount of light from the bulb, while keeping the beam that hits the fresnel appearing as if it were a simple point source.
This is not too difficult for little bulbs, but the bigger MH bulbs can sometimes impose problems due to their sheer bulk - requiring the use of different reflectors etc.
If you have ideas, don't be afraid to experiment (within reasonable costs etc.) as new ideas keep popping up, and there is no one answer yet. But, read as much of the original DIY thread as possible because it contains the combined efforts of an awesome group of people, and you might find that your ideas have already been tried.
Bill.
Other OHPs use a naked bulb, but mounted inside a reflector built in to the OHP. This reflector is designed to beam the maximum amount of light from the bulb towards the fresnel.
Either way, the fresnel is expecting to see a single point source of light - the reflectors are there to gather the maximum amount of light from the bulb, while keeping the beam that hits the fresnel appearing as if it were a simple point source.
This is not too difficult for little bulbs, but the bigger MH bulbs can sometimes impose problems due to their sheer bulk - requiring the use of different reflectors etc.
If you have ideas, don't be afraid to experiment (within reasonable costs etc.) as new ideas keep popping up, and there is no one answer yet. But, read as much of the original DIY thread as possible because it contains the combined efforts of an awesome group of people, and you might find that your ideas have already been tried.
Bill.
Just got home and measured the location for my new bulb.....i have a 5.25 inches verticle and 4.25 inches horizontal to work with......and a depth of 2.5 inches (but i can let it extend out the back of the projector in a new box.......and the aperature opening is ~2 inches in diameter......time to start deciding whats best for me.....any thoughts what i can fit in here? Originally it was a 250 MH that is long gone.
eebasist,
Did you keep the module/reflector assembly, or can you get hold of a dead one cheap?
The more you can recycle, the easier the mechanics become.
My personal preference when it comes to MH bulbs are the double ended ones. They often have mounting bolts at each end, and are usually small enough to be mounted in a reasonable sized reflector.
If you are looking for something new, the first thing to work out is what you want the light source to create - I am assuming your projector is expecting a parallel beam. This implies a spherical/elliptical reflector plus lens, or a parabolic one.
For the smaller bulbs, a parabolic reflector should be easy to rip out of a cheap headlamp/flashlamp assembly. Similarly, a small elliptic reflector could be found in the projector beam fog lamps that are quite available as add-ons.
For a bigger bulb, it gets difficult - not only to find the reflector, but also to get the beam profile small enough to feed into your projector without too many losses.
It is probably a stupid idea, but could you take a soccer ball/basket ball, use it to make a plaster spherical cavity which could have its insides coated in tinfoil; Make two holes - one to insert the bulb so that its bright spot is at the center of the spherical cavity, and another with the appropriate sized aperture so that a lens could be placed in front of it, with its focal point at the center of the spherical cavity. The resulting beam coming through the lens should be mostly parallel... ??? 😕 ???
I dunno! It would probably need cooling...
Bill.
Did you keep the module/reflector assembly, or can you get hold of a dead one cheap?
The more you can recycle, the easier the mechanics become.
My personal preference when it comes to MH bulbs are the double ended ones. They often have mounting bolts at each end, and are usually small enough to be mounted in a reasonable sized reflector.
If you are looking for something new, the first thing to work out is what you want the light source to create - I am assuming your projector is expecting a parallel beam. This implies a spherical/elliptical reflector plus lens, or a parabolic one.
For the smaller bulbs, a parabolic reflector should be easy to rip out of a cheap headlamp/flashlamp assembly. Similarly, a small elliptic reflector could be found in the projector beam fog lamps that are quite available as add-ons.
For a bigger bulb, it gets difficult - not only to find the reflector, but also to get the beam profile small enough to feed into your projector without too many losses.
It is probably a stupid idea, but could you take a soccer ball/basket ball, use it to make a plaster spherical cavity which could have its insides coated in tinfoil; Make two holes - one to insert the bulb so that its bright spot is at the center of the spherical cavity, and another with the appropriate sized aperture so that a lens could be placed in front of it, with its focal point at the center of the spherical cavity. The resulting beam coming through the lens should be mostly parallel... ??? 😕 ???
I dunno! It would probably need cooling...
Bill.
unfortunatly that kinda kills the space savings. I dont have a dead bulb, but i could advertise on ebay for one.
woneill said:
Confused too!! The lens in front of parabolic reflector would make direct part of light parallel but collimate the reflected parallel light again to a point. This mixture is unusable!!
xblocker
Hi Xblocker,
I wasn't thinking of a parabolic reflector here - instead, a spherical one.
I.e. Put the light source at the dead centre of a soccer-ball-sized sphere with internally reflecting surfaces.
Make a hole in the sphere big enough to allow a wide enough beam of light out and colimate that beam with a lens.
Basically, it is an elliptical reflector with a very round ellipse.
Attached is a sadly poor attempt to draw this... 🙁
Bill.
I wasn't thinking of a parabolic reflector here - instead, a spherical one.
I.e. Put the light source at the dead centre of a soccer-ball-sized sphere with internally reflecting surfaces.
Make a hole in the sphere big enough to allow a wide enough beam of light out and colimate that beam with a lens.
Basically, it is an elliptical reflector with a very round ellipse.
Attached is a sadly poor attempt to draw this... 🙁
Bill.
Attachments
woneill,
sorry, must have slept, you said spherical reflector.
With a spherical reflector and lightsource at the center of the sphere, which is 2xFL, you only have to create reflecting surface on that area, which is surrounded by a lines drawn from the lens's border right through the lightsource to spheric curvature.
Spherical reflectors reflect light directly back to the lightsource and create a 1:1 image of it which means double brightness.
The rest of the sphere doesn't contribute to light emission into lens's direction!
And what's about cooling?
xblocker
sorry, must have slept, you said spherical reflector.
With a spherical reflector and lightsource at the center of the sphere, which is 2xFL, you only have to create reflecting surface on that area, which is surrounded by a lines drawn from the lens's border right through the lightsource to spheric curvature.
Spherical reflectors reflect light directly back to the lightsource and create a 1:1 image of it which means double brightness.
The rest of the sphere doesn't contribute to light emission into lens's direction!
And what's about cooling?
xblocker
Hi Xblocker,
I have no actual scientific basis for proposing this arrangement, except that if only a small portion the sphere is present, then a lot of light gets lost, and if the objective is to have an external light module feeding a cannibalised projector, then we don't want to light up the room.
If nothing else, the light reflected back into the emission centre of the bulb might be re-absorbed by the charged gasses, and contribute to new emissions in a more appropriate direction. (Like I say, I have no actual scientific basis for this arrangement except that it will definitely limit stray light floating around.)
Cooling would be easy - stick a fan/blower under the base of the bulb with appropriate ducting so that air goes into the sphere from below, and out through the light exit aperture... 😉
Bill.
I have no actual scientific basis for proposing this arrangement, except that if only a small portion the sphere is present, then a lot of light gets lost, and if the objective is to have an external light module feeding a cannibalised projector, then we don't want to light up the room.
If nothing else, the light reflected back into the emission centre of the bulb might be re-absorbed by the charged gasses, and contribute to new emissions in a more appropriate direction. (Like I say, I have no actual scientific basis for this arrangement except that it will definitely limit stray light floating around.)
Cooling would be easy - stick a fan/blower under the base of the bulb with appropriate ducting so that air goes into the sphere from below, and out through the light exit aperture... 😉
Bill.
If my guess is right, this should work to prevent light loss and it would be easy to implement. But, a spherical reflector that is just right for the bulb should be more efficient. Correct?
Yes!
The sphere should be smaller and it's enough to have a half sphere! So, if you draw the said lines, the angle of captured light will increase!!
xblocker
The sphere should be smaller and it's enough to have a half sphere! So, if you draw the said lines, the angle of captured light will increase!!
xblocker
As Xblocker says, a sperical reflector wastes much light and the light bulb has double heat focused right inside bulb where fan cannot extract heat. Likely chance bulb overheats.
Cut your spherical reflector in half. Place light bulb at 1/2 radius then you getting parallel rays.
Better solution for parallel rays is traditional parabolic reflector. Unfortunately bulbs used by DIY people have larger light emmiting area than manufactured projectors with point source expensive light source so we have to make do with improvised bulb/ reflector combination to achieve best results with materials used.
Cut your spherical reflector in half. Place light bulb at 1/2 radius then you getting parallel rays.
Better solution for parallel rays is traditional parabolic reflector. Unfortunately bulbs used by DIY people have larger light emmiting area than manufactured projectors with point source expensive light source so we have to make do with improvised bulb/ reflector combination to achieve best results with materials used.
OK. So if the main point of light is at half the radius of the sphere, you'll get the desired effect and have parallel light waves?
No need for additional lenses in between that and the panel then?
No need for additional lenses in between that and the panel then?
NordicNINE,
If you are using this arrangement to drive a panel, then you will need to bend the parallel rays into a cone so that they hit the main objective lens, using a lens (probably a fresnel) either in front of, or behind the LCD. See main discussion thread.
The idea of using parallel rays here was to drive a projector which is assumed to be expecting parallel rays from its original light module.
Bill.
If you are using this arrangement to drive a panel, then you will need to bend the parallel rays into a cone so that they hit the main objective lens, using a lens (probably a fresnel) either in front of, or behind the LCD. See main discussion thread.
The idea of using parallel rays here was to drive a projector which is assumed to be expecting parallel rays from its original light module.
Bill.
Guys,
Here's an off the wall question:
It is true that in the arrangement I proposed, the light that was not used would be beamed back into the bulb - potentially causing heat build-up.
Could this phenomenon be used with a filament bulb driven at reduced power to achieve the appropriate lighting effect?
Bill.
Here's an off the wall question:
It is true that in the arrangement I proposed, the light that was not used would be beamed back into the bulb - potentially causing heat build-up.
Could this phenomenon be used with a filament bulb driven at reduced power to achieve the appropriate lighting effect?
Bill.
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