[I'm french, so please forgive mistakes in this text 🙂 ]
Hello
I'm trying to set up a CRT projector. To do that, I'm using a CRT monitor and a fresnel lens.
This is a well-known way to project an image on a wall. Many of you will tell me that the result is not as good as MH+lcd, but maybe there are some good ideas to improve the result (in total darkness, of course).
I'm using a splitted fresnel in front of the monitor. I've got some spare parts: another splitted fresnel (with shorter focal length), condenser lens, ohp triple projection lens...
I still don't find a good way to use these items in order to improve projection quality.
Could anyone have comments to have a better result? Maybe we could obtain something interesting.
Thanks to anyone who will answer to this post, and good luck to all of you in your projects.
Seeya
Hello
I'm trying to set up a CRT projector. To do that, I'm using a CRT monitor and a fresnel lens.
This is a well-known way to project an image on a wall. Many of you will tell me that the result is not as good as MH+lcd, but maybe there are some good ideas to improve the result (in total darkness, of course).
I'm using a splitted fresnel in front of the monitor. I've got some spare parts: another splitted fresnel (with shorter focal length), condenser lens, ohp triple projection lens...
I still don't find a good way to use these items in order to improve projection quality.
Could anyone have comments to have a better result? Maybe we could obtain something interesting.
Thanks to anyone who will answer to this post, and good luck to all of you in your projects.
Seeya
Throw away the TV. Buy an LCD. You have all the parts but the light and LCD.
You're wasting your time with the 100" big screen scam method. Forget about it.
You're wasting your time with the 100" big screen scam method. Forget about it.
I think you're right, faith, lcd is much better than TV
But this is my goal, I try to obtain the best image from this method.
Anyone interested can help... just for fun.
(but I repeat: I'll never say that this way is the best to have a good projector. It's only the cheapest and the easiest, I think).
But this is my goal, I try to obtain the best image from this method.
Anyone interested can help... just for fun.
(but I repeat: I'll never say that this way is the best to have a good projector. It's only the cheapest and the easiest, I think).
I bought an ancient projection CRT tv built like that.
And it's older than the scam. 😉
http://www.diyaudio.com/forums/showthread.php?s=&threadid=33010
Need a lens and curved projection screen?
And it's older than the scam. 😉
http://www.diyaudio.com/forums/showthread.php?s=&threadid=33010
Need a lens and curved projection screen?
Thank you for your link, poseablejesus. I didn't konw that such projectors were been sold ready-to-use.
For now, I've got all the stuff I need (or so think I...) but I don't know how to set up my second fresnel and my projection lens.
When I put the projection lens in front of the fresnel lens, nothing happens. I seems that projection lens is useless, and I'm sure something's wrong in my setup:
TV -> fresnel lens -> projection lens
(same result than: TV -> fresnel lens)
Would anybody have an idea on how to improve this ?
Thanx
For now, I've got all the stuff I need (or so think I...) but I don't know how to set up my second fresnel and my projection lens.
When I put the projection lens in front of the fresnel lens, nothing happens. I seems that projection lens is useless, and I'm sure something's wrong in my setup:
TV -> fresnel lens -> projection lens
(same result than: TV -> fresnel lens)
Would anybody have an idea on how to improve this ?
Thanx
I didnt know they ade them like that either, until I cracked this one open.
Even then, HEZZ had to help shine some light on it for me.
You'll notice in the link I posted, that the TV had no fresnel at all, the Lens does all the magnifying.
:shrug:
Even then, HEZZ had to help shine some light on it for me.
You'll notice in the link I posted, that the TV had no fresnel at all, the Lens does all the magnifying.
:shrug:
I'd like to see pics if you manage to get a watchable picture out of it. I tried doing that a few years ago, with a lense at first and again with a fresnel, but even in total darkness it was very dim and way out of focus at the edges. Not to mention backwards as well. I was using a 14" tv with the brightness cranked. It was fun to play around with. If you had a flat crt tv or monitor, it might look ok, but there is still the brightness issue.
Be sure I'll post pics of my results, if I can get a... watchable picture...
Edge focus doesn't seem to be a problem, because I use a flat CRT monitor (very cheap since lcd apparition on the market).
The real problem (and it's not a surprise for everyone here) is the very tiny light source. Total darkness is not a problem for me, because I want to watch movies (no TV programs or computer games), so this will help a little.
After reading your comment, poseablejesus, I decided to do the following:
1 - use only magnifying lens, and throw away fresnel lens (maybe I'll re-use them later)
Maybe someone can help: I'm using a triplet magnifying lens, maybe I should use only one lens. I still don't know what's the best way, I'm gonna try by myself.
2 - Try to add splitted fresnel... and see what's happening... 🙂
As I previously said, be sure I'll post pics if anything good happens.
(In fact, I'll post pics even if projected pictures are the worst ever seen... It'll show results for beginners who didn't made this before and for the more experienced users... they'll have a good laugh 😀 )
Edge focus doesn't seem to be a problem, because I use a flat CRT monitor (very cheap since lcd apparition on the market).
The real problem (and it's not a surprise for everyone here) is the very tiny light source. Total darkness is not a problem for me, because I want to watch movies (no TV programs or computer games), so this will help a little.
After reading your comment, poseablejesus, I decided to do the following:
1 - use only magnifying lens, and throw away fresnel lens (maybe I'll re-use them later)
Maybe someone can help: I'm using a triplet magnifying lens, maybe I should use only one lens. I still don't know what's the best way, I'm gonna try by myself.
2 - Try to add splitted fresnel... and see what's happening... 🙂
As I previously said, be sure I'll post pics if anything good happens.
(In fact, I'll post pics even if projected pictures are the worst ever seen... It'll show results for beginners who didn't made this before and for the more experienced users... they'll have a good laugh 😀 )
Hi there,I have set one of those up and watching it for several months.I am using 15"monitor with a TV box as a picture source,the projection setup is a diy box ,inside this box have a mirror and two fresnel,the monitor's screen face down to the mirror,the mirror set to 45digree and refected the light to the fresnels,the two fresnel should separate about 40cm and in a same axis ,the main point is those two fresnel 's grooved side must face to the mirror!!.
It did watchable in a total darkness environment and focus well,what i am searching now is a brightor 15" flat monitor to get better result.I am thinking too is a 21"flat monitor setup.
It did watchable in a total darkness environment and focus well,what i am searching now is a brightor 15" flat monitor to get better result.I am thinking too is a 21"flat monitor setup.
Hi bjou, thanx for you comments.
I tried using only projection lens. The picture has good quality but is far too dim.
So I'm gonna use fresnel lenses, in the way you told me.
I don't have a mirror, and I don't know if it's really useful. Maybe it was used only for design purposes ?
I'll tell here what I get.
seeya
I tried using only projection lens. The picture has good quality but is far too dim.
So I'm gonna use fresnel lenses, in the way you told me.
I don't have a mirror, and I don't know if it's really useful. Maybe it was used only for design purposes ?
I'll tell here what I get.
seeya
This thread really needs to move to the msn forums where this type of projector is supported. At least there you might get some optomistic replies.
Most folks around here know it is really a waste of time...
Most folks around here know it is really a waste of time...
Dangit I can't find the link. I had a pc meltdown today and had to reinstall windows, and lost some favorites in the process. Someone post a link to the msn diy tv projector forums. I don't know what lens they're on now, as I haven't been on there in a long time, but last I was there they were all hyped about simple meniscus lenses. Who knows what they like now.
I'm gonna search for this link, faith.
I already got some interesting results with two fresnel lenses.
I'm also trying to improve THT settings on the TV, this could be a good solution I think. I'll get more light if I succeed (... and I will loose my TV if I fail 😀 )
I already got some interesting results with two fresnel lenses.
I'm also trying to improve THT settings on the TV, this could be a good solution I think. I'll get more light if I succeed (... and I will loose my TV if I fail 😀 )
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