DIY Video Projector

[woneill]

Hi Gunawan,

Your issue about distortion was the reason I mentioned keeping the "eye point" close to the lens - roughly somewhere between the lens and its focal point.

If the view point was too far away from the lens, the limitations of fresnel technology caused MASSIVE distortion of the image with the corners either being distorted horribly or simply blotted out depending on which way the grooves were facing.

I got best results with the grooves facing the panel.

The concave lens was used because even with a longer throw objective, it was outside the optimal image "collection point" of my fresnel. I.e. it was far enough away from the fresnel that the gross distortions mentioned above kicked in. The concave lens polaced closer to the fresnel collected the light and "elongated" the "cone" such that the objective could operate within its normal parameters and not get hit by the gross distortions of the fresnel.

Each fresnel is different - with different focal length and line spacing. Some longer focal length ones might be better without the concave step. The one I was playing with definitely needed something to collect the light, and forward it to the objective.

Bill.

[thelaw]

Woneill:

Let me first congratulate you on the first rate information you are providing to the forum.

Also, i would advise against the slow startup/shutdown of Quartz lamps. I tried this myself using servos later to find out info that would make impossible. Quartz halogen lamps use special chemicals on the filament that are activated by the heat. As these chemicals are expecting the full voltage/amp input and a high amount of heat they will attempt to disperse some of the heat accordingly. If less the the full voltage/amp amount is fed through the lamp there will not be enough heat, thus the chemicals will instead be attacking the filament, leading to early lamp failure.

Thought i'd mention it to save u a few $

I'm currently looking for a 400W MH double ended lamp and ballast for my OHP. My OHP is an Elite Vision 4000 and was designed for LCD use and has a plug outlet on the front of the unit for an LCD panel. It has a condensor lens just above the lamp assembly so i cannot fit a full sized spherical lamp in the space. It currently takes 400W 50hr EVD lamps, which give out 16,000 lumens. A 400W mh would increase this to around 38,000 which should hopefully give a nicer picture.

Does anyone know where i could get such a lamp/ballast?

Cheers,

[vdi_nenna]

To All,

When I started this thread I didn't think anyone would be interested. I thought maybe 10 people in the world would respond. But like Drill Sergent Hartman said in Full-Metal Jacket, "I'm glad to see that you have grown beyond our control."
It has grown into a monster thread that is out of control, but now it must come to an end.

I think there is enough here for anyone to attempt to build their own DIY projector. This site has a search feature that everyone should embrace. Web sites are popping up on the subject, so this should be another source of information. And, let's not forget E-mail. I still recieve on average 2 emails a week with questions, and I have not contributed in months to this thread.

Maybe the devoute can create a web ring, email list or a news group on the topic.

This is not to say, no one should post regarding DIY projectors. To the contrary. I'm just saying this thread is getting tired.

Take what you know and build on it.

Always remember to help each other and make it fun. Don't forget to respect each other too. The world is watching.

Best regards,

Vince Di Nenna

[snoogans]

vince,

why close the thread? So many people contribute to it. Just because you have lost interest doesn't give you the right to close the thread.




regards,
snoogans

[clok]

since everybody seems to read this forum and it sounds like this thread my die, thought i would post this here.

Im currently compiling a FAQ and links and such from this thread and other Websites. Just wanted to say im going to mention a few of your "screen" names in the thank you, and some of your information. If any of you DO NOT want your "screen" name ( no e-mail address's (dont worry) or webpages, or even your ideas posted in this FAQ please let me know.

PLEASE DO NOT E_MAIL me for the FAQ.. i will post it when its done..

clockwork@uswest.net

Clok

[vdi_nenna]

snoogans,

I haven't lost interest. I don't think my ideas travel the same "thread" as others on this...thread, but that has nothing to do with it. If it did, I would have shut it down a long time ago.

The thread is entirely too long and people do not use the search function to find answers, they just keep asking the same questions over and over again. That's fine, if you have unlimited bandwidth and disk space to give away.

People are joking around and going on tangents, posting stupid pictures and then insulting each other.

I was asked by a moderator to consider closing the thread for other reasons. Their suggestion alone is good enough for me and I will respect it.


It's been a nice run, Boy and Girls. Thanks for contributing!

This thread will be closed tomorrow morning EST.

See you,

Vince

[woneill]

Thanks TheLaw,

No point wasting more money on bulbs than necessary...

I don't know of any double-ended 400W MH bulbs. Most double-ended stuff seems to be set for weird wattages with hard to find ballasts.

This link seems to cover the spread of weird MH bulbs that I am aware of:

http://www.eurotekmarketing.com/index.html

Bill.

[snoogans]

vince,

i'm sorry i misunderstood your post, and now i see your point, and agree completly, this thread is too long.

Sorry for the misunderstanding


Snoogans

[contrapasta]

Its funny how easily some people get on power trips. Your closing a thread that you admit you haven't been a part of lately? Its obvious that other people seem to like the thread.

This would be simular to starting a conversation at a party, then trying to close the conversation long after other people have started in on it and continued it after you left. What sense does that make expect that it is a power trip for you, that you have the ability to create and destroy. (I think of it as more a technicality of how the forum was setup)

If it is a money thing, then fine, I can understand if the bandwidth is too much (is DIY Audio complaining?), but not for one person just getting some sought of feeling that it should be shut down.

So what if you left the converstion and on to something else, others are just joining or are still interested. Let the thread die when intrest for the thread dies. Of course you have no power over that that, now do you?

[Marklar]

Am I the only one that thinks "Hey why don't someone start a new thread"?