I thought to start a new thread on the reflector since the info on elliptical or other types of reflectors is scattered on several threads.
My original thread on MH lamp has been slowly diverting on the reflector side and has some info on the reflectors design and trials, see:
http://www.diyaudio.com/forums/showthread.php?s=&postid=98024#post98024
My original thread on MH lamp has been slowly diverting on the reflector side and has some info on the reflectors design and trials, see:
http://www.diyaudio.com/forums/showthread.php?s=&postid=98024#post98024
I found one!
Well after destroying $12.00 worth of bowls I found an eliptical reflector 🙂 The shop had $75.00 on it for the rflector and a 250 watt ballast. I asked him if he'd take 30 for just the reflector as I didnt need yet another ballast. He gave it to me for $25.00 and threw in a couple of Sylvania bulbs for real cheap. The Sylvania's seem to throw much better light than the GE's, cleaner if that makes sense (or is it the reflector?).
This PJ is going to be HUGE so I'm going to use undreams idea of the tower style PJ, with a slight differance, my light will be on the TOP of the tower. The ballast and the dedicated HTPC will be mounted in the bottom(vented) with the LCD and such in the middle.
I'm hoping that this will keep MUCH of the bulb heat from making it's way to the LCD.
The reflector is painted white, it's alluminum, should I chemically strip the paint and polish it ?
zardoz
Well after destroying $12.00 worth of bowls I found an eliptical reflector 🙂 The shop had $75.00 on it for the rflector and a 250 watt ballast. I asked him if he'd take 30 for just the reflector as I didnt need yet another ballast. He gave it to me for $25.00 and threw in a couple of Sylvania bulbs for real cheap. The Sylvania's seem to throw much better light than the GE's, cleaner if that makes sense (or is it the reflector?).
This PJ is going to be HUGE so I'm going to use undreams idea of the tower style PJ, with a slight differance, my light will be on the TOP of the tower. The ballast and the dedicated HTPC will be mounted in the bottom(vented) with the LCD and such in the middle.
I'm hoping that this will keep MUCH of the bulb heat from making it's way to the LCD.
The reflector is painted white, it's alluminum, should I chemically strip the paint and polish it ?
zardoz
I should probably add a summary of some of my experiences from Rajkumar's other thread:
I was trying to make of a light source employing the cheapest of the 400w MH bulbs; the well-known 11x4.5" mogul-based monster.
I tried several methods of hand-making a "rectangular" (ie half-pipe) ellipsoidal reflector, using a number of designs and a few different reflective materials. My designs ranged in focal depth from 6" to 30", and in reflector size (height X width) from 12x14 to 20x36. The result of 4 different prototypes is either (a) it's almost impossible to capture enough light from one of these bulbs using a reflector, or (b) I _really_ don't know what the heck I'm doing. I had some semi-successes, where the light source was mildly better than a standard OHP, but nothing that indicated I was getting a reasonable % of the available 36K lumens.
I have now resorted to searching for other sources for ellipsoidal bowls that may be used as reflectors. One possibility was mentioned some time ago on this board: Kitchen mixer bowls. Another possibility is using a spherical mixing bowl to create a parallel beam. Due to the dimensions of this bulb, I need a minimum of 10-12" diameter, and a depth of about 12", in either case.
Anyways, that's where I am with the experiment.
I was trying to make of a light source employing the cheapest of the 400w MH bulbs; the well-known 11x4.5" mogul-based monster.
I tried several methods of hand-making a "rectangular" (ie half-pipe) ellipsoidal reflector, using a number of designs and a few different reflective materials. My designs ranged in focal depth from 6" to 30", and in reflector size (height X width) from 12x14 to 20x36. The result of 4 different prototypes is either (a) it's almost impossible to capture enough light from one of these bulbs using a reflector, or (b) I _really_ don't know what the heck I'm doing. I had some semi-successes, where the light source was mildly better than a standard OHP, but nothing that indicated I was getting a reasonable % of the available 36K lumens.
I have now resorted to searching for other sources for ellipsoidal bowls that may be used as reflectors. One possibility was mentioned some time ago on this board: Kitchen mixer bowls. Another possibility is using a spherical mixing bowl to create a parallel beam. Due to the dimensions of this bulb, I need a minimum of 10-12" diameter, and a depth of about 12", in either case.
Anyways, that's where I am with the experiment.
I dont think the rectangular ellipsoidal would work. Light would bounce out on any point not perpendicular.... All light needs to be redirected towards a common point.
I just got on break, going to start my first experiments in casting before I move on to casting a big ole freaking huge 18 inch diameter ellipsoidal with builtin water cooling channels.
Myren.
I just got on break, going to start my first experiments in casting before I move on to casting a big ole freaking huge 18 inch diameter ellipsoidal with builtin water cooling channels.
Myren.
Myren,
Yep, I can back up your theory of "rectangular" reflectors not working with 4 failed experiments 😉 I was able to focus the light, but just not enough of it.
Yep, I can back up your theory of "rectangular" reflectors not working with 4 failed experiments 😉 I was able to focus the light, but just not enough of it.
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