DIY Video Projector Part II - Page 54

jco9w · 3rd August 2002, 10:13 PM

For those of you who would like to use multiple lamps to get more light: Couldn't we setup the lamps behind a fresnel that would catch almost all their light, and focus it, and then at the focal point, we could put a diffusing lense (I am sure this isn't the right word, but I don't know the name of it), like the ones in the Elmos HP A305's, and 3M 9550 OHP's. For those of you who haven't seen these diffuser lenses, these lenses are real thick and go right in front of the bulbs in these projectors. This technique would conentrate relatively diffuse light, and then diffuse it out onto another fresnel, and the LCD panel.

Lamps Fresnel Diffuser Fresnel LCD Objective
} |
} | ) | LCD ()(
} |

This should allow you to use multiple light sources without hotspotting, I think.....

An update on my work: I got a fresnel, a diffuser lens and an objective lens from Inventory Solutions on Friday. I now have everything I need to build the projector. The objective I got has a variable focal length, you just rotate the mount to change the focus. This means I woun't have to have a moving part to the front of my box, which is a key!

Current parts:

Nview MediaPro LCD panel
4 1/2 in elliposidal downlight reflector
diffuser lens from Elmo HP A305
triplet objective lens from Elmo HP A305
fresnel from Elmo HP A305
400 Watt MH BT 28 bulb with MultiTap M59 ballast

My setup will be very similar to Marlakar's, but hopefully smaller!

J

jco9w · 3rd August 2002, 10:15 PM

I was at Advance autoparts the other day, and noticed that they have chrome tape. It is very shiny tape, that could be used as part of a reflector, I think.

they also had aluminum tape, but not as shiny.

If you get a good mold, you could just use this tape? Not sure how well it would stand up to heat, though.

J

Mitch · 3rd August 2002, 11:47 PM

Where did Redevil Go? I`d like to find out more about his projector. If he`s getting a really good image, then ignoring his ideas would be really dumb...

xblocker · 4th August 2002, 02:14 AM

Concerning new ideas of reflectors: You guys should do a google search for 'solar cooker'. There are a lot of reflectors out there...!
Well, if they are good enough for optical instruments is another question, but it's worth a look!

xblocker

mycamel · 4th August 2002, 03:08 AM

Quote:

Originally posted by woneill
Even a crude and simple arrangement such as this would be better than most of the existing reflectors out there

I guess the only real reason for pursuing our own reflector is to allow us to try optimizing the light from the 'cheap' 400w MH bulbs.

Got another question, but being that its reflector oriented, I'll take it over to the reflector thread.

Redevil · 5th August 2002, 03:50 AM

Hey Mitch
Just got back from trip.
Use a magnifying lens at end of bulb.
Using only 640x480 LCD panel.
Image looks perfectly good all around.
Make sure to build heat sink around ballast, gets hot.
Fan the bulb.
Then your good to go.
Later

Undream · 5th August 2002, 04:20 AM

My latest creation. $8 and 3 hours.

I havent mounted the bulb permanently in it yet. But, its going to be easy. Plastic planter and a plastic bowl, purchased at Walmart for $1.97 and $.50, respectively. I also havent done any testing with it yet (havent even hooked up the bulb.
But, it looks very promising.

Undream · 5th August 2002, 04:21 AM

couple more pics.

Mitch · 5th August 2002, 05:03 AM

Redevil,
I have some questions about your particular design.

How long is the entire structure? What is the distance between the two fresnal lenses you use for light dispersion?
Also, what size is your LCD? I want to use a 14", but I have a 3 7/8" plano convexlens that was made for a Mitsubishi projection tv. Do you think that`ll be big enough to "suck in" the entire image of the 14", or will I need a bigger one?

Mitch

Biglurchy · 5th August 2002, 05:38 AM

Quote:

Originally posted by mycamel

Any adhesive experts among us? What sort of heat does super-glue handle? Would it start producing toxic fumes after we'd been watching our TV a while? Are there any epoxies made for automotive repair that could handle the heat?

A good heat resistent epoxy solution would be JBweld, it has been used in many automotive applications including use on the egine block. How much heat it can stand exactly I'm not sure.

I'm almost certain superglue would break down past 120 degrees fahrenheit . Also doesn't seem like it would bond well to foil. JBweld will bond to most anything.

I work for a tool store and have access to a huge resorce of knowlege, coming from experts in all aspects of hardware related fields. Feel free ask any questions such as the "quote" above, and I'll do my absolute best to get the answers you need.

You guys have been a great help in my own project (still on paper), and would like to contribute as much as possible.

3rd August 2002, 10:13 PM	#531
jco9w diyAudio Member Join Date: May 2002 Location: Virginia	sure this has been thought of before For those of you who would like to use multiple lamps to get more light: Couldn't we setup the lamps behind a fresnel that would catch almost all their light, and focus it, and then at the focal point, we could put a diffusing lense (I am sure this isn't the right word, but I don't know the name of it), like the ones in the Elmos HP A305's, and 3M 9550 OHP's. For those of you who haven't seen these diffuser lenses, these lenses are real thick and go right in front of the bulbs in these projectors. This technique would conentrate relatively diffuse light, and then diffuse it out onto another fresnel, and the LCD panel. Lamps Fresnel Diffuser Fresnel LCD Objective } \| } \| ) \| LCD ()( } \| This should allow you to use multiple light sources without hotspotting, I think..... An update on my work: I got a fresnel, a diffuser lens and an objective lens from Inventory Solutions on Friday. I now have everything I need to build the projector. The objective I got has a variable focal length, you just rotate the mount to change the focus. This means I woun't have to have a moving part to the front of my box, which is a key! Current parts: Nview MediaPro LCD panel 4 1/2 in elliposidal downlight reflector diffuser lens from Elmo HP A305 triplet objective lens from Elmo HP A305 fresnel from Elmo HP A305 400 Watt MH BT 28 bulb with MultiTap M59 ballast My setup will be very similar to Marlakar's, but hopefully smaller! J

3rd August 2002, 10:15 PM	#532
jco9w diyAudio Member Join Date: May 2002 Location: Virginia	forgot to add this I was at Advance autoparts the other day, and noticed that they have chrome tape. It is very shiny tape, that could be used as part of a reflector, I think. they also had aluminum tape, but not as shiny. If you get a good mold, you could just use this tape? Not sure how well it would stand up to heat, though. J

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3rd August 2002, 11:47 PM	#533
Mitch diyAudio Member Join Date: Jul 2002 Location: Indiana, USA	Where did Redevil Go? I`d like to find out more about his projector. If he`s getting a really good image, then ignoring his ideas would be really dumb...

4th August 2002, 02:14 AM	#534
xblocker diyAudio Member Join Date: Dec 2001	Concerning new ideas of reflectors: You guys should do a google search for 'solar cooker'. There are a lot of reflectors out there...! Well, if they are good enough for optical instruments is another question, but it's worth a look! xblocker

5th August 2002, 04:20 AM	#537
Undream diyAudio Member Join Date: Apr 2002 Location: Adrian, MI	My latest creation. $8 and 3 hours. I havent mounted the bulb permanently in it yet. But, its going to be easy. Plastic planter and a plastic bowl, purchased at Walmart for $1.97 and $.50, respectively. I also havent done any testing with it yet (havent even hooked up the bulb. But, it looks very promising.

5th August 2002, 04:21 AM	#538
Undream diyAudio Member Join Date: Apr 2002 Location: Adrian, MI	couple more pics.

5th August 2002, 05:03 AM	#539
Mitch diyAudio Member Join Date: Jul 2002 Location: Indiana, USA	Redevil, I have some questions about your particular design. How long is the entire structure? What is the distance between the two fresnal lenses you use for light dispersion? Also, what size is your LCD? I want to use a 14", but I have a 3 7/8" plano convexlens that was made for a Mitsubishi projection tv. Do you think that`ll be big enough to "suck in" the entire image of the 14", or will I need a bigger one? Mitch

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