DIY Rear Projection TV

[nmd_sb]

also in Home Depot (Hardware store) I have seen white translucent plastic board, I dont know what its used for, I am guessing Kabuki theatre or strip tease maybe.

I bet that will also work great.

 

[ds21]

Has anyone used a screen from Harkness Hall, there pretty cheap.

I got lucky at work the other day. I know the A/V guy at work pretty well, and they have an 1997 RCA 60" RP that they've had to fix one to many time, and he gave me first dibs on it. I should have it home next weekend and gut it out, once I get my projector inside and working, I get one of the "Harkness Hall" screens to do a comparison, if it's good I'll construct a bigger unit.

 

[nmd_sb]

hi ds21
if you're not going to use teh RCA lens, can I have it?

 

[ds21]

nmd_sb, I'll keep you in mind.

 

[ace3000_1]

hehehe wow! have a look at that mother of a frensel, i thought i throw this link in here as this place makes custom frensels and custom sizes, not sure of the price though will need to email them, would be good for a screen.

http://www.ntkj.co.jp/products-e.html

Trev

 

[ds21]

rmccoll,

you night want to check this out, could solve your problems with the hotspot, it's a large Fresnel lens 31" x 40" it's the cheapest I've found, and it's light so shipping shouldn't be much.

http://sales.goldmine-elec.com/prodinfo.asp?prodid=9039

if you want bigger! here's one 38" x 50" for $100 plus a lot for shipping:

http://www.alltronics.com/lenses.htm

Havn't found a good place for a Lenticular lens (the grooved one that you feel on the front, but I'm thinking you can get by without it (it the lens that spreads the light out to the sides for viewing of angle) just put the Giant frenel behind what your using now.

I just did a quick test with my gutted 60" RCA and can say this will look incredibe!!! I only live in a small appartment so the limit of 60" is no problem for me. just have to figure out new optical arangment to shorten focal length so I can fit it all inside the TV.

 

[rmccoll]

Thank you, Thank you And Thank you again, you just saved me alot of time, I was going to use a dremel and a circle guide to cut every little grove into a sheet of plexi-glas to try and make a fresnel lense you savee me alot of time.

 

[rmccoll]

Now that I have a large fresnel lense I'm going to rebuilt my tv to make it look more professional and brighter. I'm also rebuilding my projector using a gameboy adavnce screen I know people will say that my picture will have a low resolution but I bought a A/V adapter from www.lik-sang.com and was convinced, the picture it produce was better than I thought for a resolution of 160X240 that only equals 38400 pixels, but I'm going with it, I'm just trying to get it built.

 

[rmccoll]

Its been awhile since I have posted but I have made alot of progress. Instead of using a gameboy advance as my screen I'm using a Casio portable TV it's 3'' inches and the resolution is 115,000 which is good enough for me it's way better than 39,800. For my light Iam using a 100 watt halogen bulb it's really small about 3 inches long by 2 inches high. I'm using a condesner lense system I got from a old slide projector because they are 2 in. in diameter and it focus light really well.
I will post picture of my setup tomorrow. I ordered a camera from ebay and it should arrive tomorrow.

 

[freeupyermind]

If your into the whole rear projection thing then here's something for you to aspire to!

 

[freeupyermind]

instead of using a big mirror, could u use a big peice of plexiglass covered in mylar to transfer the image from the projector to the screen?

 

[rmccoll]

Yeah I thought about it but it would be easier to buy a plexi-glass mirror.
You can buy them form www.usplastics.com you might want to check this site too they sell everything literally they sell everything, ballast for MID bulbs and the bulbs check them out www.mcmasters.com

 

[dbc105]

I use to own a rear project tv but some part went bad and it was going to be $600 for parts. I guess my buddy that looked at it still has it in his shop. has anyone used a bad big screen tv and just put a lcd setup in it? the screen and lense are aready there. any thoughts on this would be a help. I am going to try to call him this weekend and see if he still has it.
David
dbc105

 

[rmccoll]

I guess it can work. What size is the screen? If going to use a computer LCD you would need to use a lense with a low focal length to get the projected image to fit the screen.

 

[dbc105]

the screen is 50" to 55". will I have to use a wide screen LCD and if it has a lense inside do you think I could use it? if not how do I figure focal length? I am going to give him a call today to see what he has sitting in his way. if I can make it work it sure would save a lot of work.
David
dbc105

 

[PeterMitchell]

rmccoll

I know this is a bit off-topic, but I have a Fujinon 4 1/2 lense collecting dust. Just wanted to know if you consider the 4 inch Psone lcd (assuming that is the one you use) decent for projecting purposes (not rear projecting)? Would be nice to build a cheap projector to project a 50-60" image considering the psone screens are so inexpensive.

Seems to me you get a decent picture disregarding the dark sides. Would it be possible to project an image on to a normal screen (not rear projecting) and up a picture of it here?

 

[goldmoth]

I have a used fresnel from a old big screen. I played around with it a while back using my ohp setup. I suppose the reason rptv manufacturers use a large fresnel instead of a standard grey translucent screen like what is normally used for lcd rear projection is the hot spot problem. Bright in the middle dark on the sides. I have a high quality projection tv, but I can say that I would prefer to use a standard grey screen, with the fresnel you have viewing angle problems and it seems muddier than rear projected lcd images I have seen.. anyone have ideas on how to use a grey screen instead of a big *** fresnel?

 

[dbc105]

well I got in touch with my buddy and he has several rear projection tv's he is going to throw out. in selecting a case what do I need to look for? type of lenses, fresnels, screens, etc? any and all help is greatly appreciated.
David
dbc105

 

[mbates14]

i have an old 48" fresnel collecting dust around here. its a little scratched, but i guess it works. it just sits and collects dust.

 

[rmccoll]

Sorry I have not post but I just entered college and just got my internet connection on. The Psone lcd will work I used the sony brand 5 inch lcd for my first one.