ive been reading quite alot during these last weeks here and i can say that this forum rocks 🙂
so i think im ready to start planning my first pj
i got an original psone lcd which im going to mod ( the vga and other picture improving mods.. )
and im going to start going to garage sells and markets to see what can i find there that can help me
im trying to do this as cheap as i can
i think ill spend 100$ max and if i can less then i will hehe 🙂
so i got a few questions before i go out and start looking for stuff
my room is not that big and i want to know if a regular ohp lense will be ok for me
i got an area that i can project to which is 1.5mx2.5m ( WxH ) aprox.
so from my calculation
if i project to a 1.5m ( i got like 1.6-1.65 so it will be viewable ) width
at a ratio of 4:3
the projection will be 1.125m high
so ill get a projection of 70 inch aprox. (73.88 to be exact 🙂 )
the length from the wall where the projection box will be mounted on ( and the viewers will seat ) to the projection screen is 3.3m aprox.
my questions are :
1.first of all are my calculations correct? 🙂
2.is a 70 inch picture can be viewable from a distance like 3.30m and with a 5" screen or should i go for less like 50-60"?
3.will a regular triplet lens from an ohp be ok for me or do i need to search for a specific one with specific fl and stuff like that?
if yes please give me the specification so i can start looking
4.i havent inserted the box measurments to the calculations cuz i dont know which lamp and lenses ill use but whats the aprox. box measurements a 5" lcd is needed?
*im planning to put a focus system so it will be portable and ill be able to move it to other rooms if ill need
thanks alot in advance 🙂
btw i saw lots of you use inches so to make it easier for u here is a calculator that can turn inches to cm and otherwise
http://annica.in-cyberspace.net/en/inch_cm.html
so i think im ready to start planning my first pj
i got an original psone lcd which im going to mod ( the vga and other picture improving mods.. )
and im going to start going to garage sells and markets to see what can i find there that can help me
im trying to do this as cheap as i can
i think ill spend 100$ max and if i can less then i will hehe 🙂
so i got a few questions before i go out and start looking for stuff
my room is not that big and i want to know if a regular ohp lense will be ok for me
i got an area that i can project to which is 1.5mx2.5m ( WxH ) aprox.
so from my calculation
if i project to a 1.5m ( i got like 1.6-1.65 so it will be viewable ) width
at a ratio of 4:3
the projection will be 1.125m high
so ill get a projection of 70 inch aprox. (73.88 to be exact 🙂 )
the length from the wall where the projection box will be mounted on ( and the viewers will seat ) to the projection screen is 3.3m aprox.
my questions are :
1.first of all are my calculations correct? 🙂
2.is a 70 inch picture can be viewable from a distance like 3.30m and with a 5" screen or should i go for less like 50-60"?
3.will a regular triplet lens from an ohp be ok for me or do i need to search for a specific one with specific fl and stuff like that?
if yes please give me the specification so i can start looking
4.i havent inserted the box measurments to the calculations cuz i dont know which lamp and lenses ill use but whats the aprox. box measurements a 5" lcd is needed?
*im planning to put a focus system so it will be portable and ill be able to move it to other rooms if ill need
thanks alot in advance 🙂
btw i saw lots of you use inches so to make it easier for u here is a calculator that can turn inches to cm and otherwise
http://annica.in-cyberspace.net/en/inch_cm.html
Welcome to the forum!
Once again - I suggest a big CRT projector lens for PS1 and other lcds that are 5 inches or less - CRT lenses are very efficient (bright), have short focal lenghts (good for a small LCD, maybe too short for you), have a built in focusing system (easy build), low costing - about $15 usually (save money!), placed right against the screen (more compact projector), cover the whole lcd (no need for a front fresnel), many have mounting holes (again - easy build), and so on. You gotta make sure the lens covers the entire LCD (i.e. its not too small), or else you will have the corners clipped off, lol.
Good luck on your build!
Once again - I suggest a big CRT projector lens for PS1 and other lcds that are 5 inches or less - CRT lenses are very efficient (bright), have short focal lenghts (good for a small LCD, maybe too short for you), have a built in focusing system (easy build), low costing - about $15 usually (save money!), placed right against the screen (more compact projector), cover the whole lcd (no need for a front fresnel), many have mounting holes (again - easy build), and so on. You gotta make sure the lens covers the entire LCD (i.e. its not too small), or else you will have the corners clipped off, lol.
Good luck on your build!
wow thx man
ill search for a crt projector lens ( crt projector is an overhead projector or they are 2 different projectors? )
any specification on the focal length and other stuff that i need the lens to be or any regular crt lens will do ok?
and last question
can u post a diagram of the build u suggest me?
if i undrestand it correct i only need the lens , a lamp and the lcd?
i got the lumenlab guide so most of my ideas are from there..
thx again 🙂
ill search for a crt projector lens ( crt projector is an overhead projector or they are 2 different projectors? )
any specification on the focal length and other stuff that i need the lens to be or any regular crt lens will do ok?
and last question
can u post a diagram of the build u suggest me?
if i undrestand it correct i only need the lens , a lamp and the lcd?
i got the lumenlab guide so most of my ideas are from there..
thx again 🙂
Glad to help.🙂
oh an ohp and a crt projector are completely different.
look them up at google (in the images search)
For a basic design with a crt lens you'll need - light, rear fresnel, lcd, fan, crt lens.
Here - I quickly drew up a design for a ps1 projector. Its not the best, and can vary plenty, I think some more senior and experienced members can fill you in on the details, or a better design, lol.
Once again - Good luck!😀
oh an ohp and a crt projector are completely different.
look them up at google (in the images search)
For a basic design with a crt lens you'll need - light, rear fresnel, lcd, fan, crt lens.
Here - I quickly drew up a design for a ps1 projector. Its not the best, and can vary plenty, I think some more senior and experienced members can fill you in on the details, or a better design, lol.
Once again - Good luck!😀
Attachments
ancorp said:
niceee 🙂
yeh ive searched it up and now i know whats the difference
now i just got to find out where can i get it in israel hehe
thx alot for ur help
just one question about the design
short fl frensel - how much is short?
i got a rogers page magnifier from office depot ( from when i built the tv projector ) will it do ok? it doesnt say what fl it is or anything
its a 7"x10" sheet
thx again 🙂
fresnel focal lengths
Most people use 220 mm or 200 mm focal length for their lower fresnels. Those work well for even 17" LCDs. But for a small screen like the PS1, I would use the shortest focal length fresnel lens I could find. The shorter it is, the closer you put it to the light source, so it will intersect more of the light.
You can measure the focal length of a fresnel lens, just like any other positive lens: Hold it smooth side to the sun, move it until you get the smallest image (like cooking an ant with a magnifer), then measure the distance between the lens and the image.
If the office supply store has fresnels rated in "power", then you want the highest power. (Like 5X) If they are rated in Diopters, highest = shortest focal length and:
Diopters = 1000 / focal length in mm
Watch out for page magnifiers that have a little "super magnifier" circle in one corner. That has to be removed when you cut out the center part you need for your projector.
Most people use 220 mm or 200 mm focal length for their lower fresnels. Those work well for even 17" LCDs. But for a small screen like the PS1, I would use the shortest focal length fresnel lens I could find. The shorter it is, the closer you put it to the light source, so it will intersect more of the light.
You can measure the focal length of a fresnel lens, just like any other positive lens: Hold it smooth side to the sun, move it until you get the smallest image (like cooking an ant with a magnifer), then measure the distance between the lens and the image.
If the office supply store has fresnels rated in "power", then you want the highest power. (Like 5X) If they are rated in Diopters, highest = shortest focal length and:
Diopters = 1000 / focal length in mm
Watch out for page magnifiers that have a little "super magnifier" circle in one corner. That has to be removed when you cut out the center part you need for your projector.
Design Challenges
There are a few design challenges in this project to over come. I made my lcd mount and realized due to the short ribbon cable I was going to have issues with my controller board. T
The first being that I need reverse and flip the screen which puts the control board in the path of the massive CRT lense. I already reversed the board but it still is in the way....
I am working on a solution, but it might just not fit with out some sort of extension for the ribbon cable.
There are a few design challenges in this project to over come. I made my lcd mount and realized due to the short ribbon cable I was going to have issues with my controller board. T
The first being that I need reverse and flip the screen which puts the control board in the path of the massive CRT lense. I already reversed the board but it still is in the way....
I am working on a solution, but it might just not fit with out some sort of extension for the ribbon cable.
If you intend to use your projector in conjunction with your computer an easy solution would be to use software to rotate/flip the image allowing you to fit the lcd so as not to be in the way of your lens 🙂
Wow - Guy just pretty much covered it all, damn!
Once again - Im waiting for "How to build an LCD projector" - by Guy Grotke🙂
I hate rotating on the computer - some things can be not compatable (video/tv out, etc), some things will slow down, perhaps video as well, because overlay may not work rotated... alot of issues, not worth it, better to redesign the projector to project propertly. Plus if you rotate on the pc, if you want to play any gaming console, or watch a vhs or dvd from a dvd player, you will have to pass it through a tv card on your computer...
Sucks!😀
Once again - Im waiting for "How to build an LCD projector" - by Guy Grotke🙂
I hate rotating on the computer - some things can be not compatable (video/tv out, etc), some things will slow down, perhaps video as well, because overlay may not work rotated... alot of issues, not worth it, better to redesign the projector to project propertly. Plus if you rotate on the pc, if you want to play any gaming console, or watch a vhs or dvd from a dvd player, you will have to pass it through a tv card on your computer...
Sucks!😀
re
Yea, that is pretty much my thoughts. I have it figured out I think. I am gonna play some more over the weekend and see what I can get working. It is gonna be close though lol
I goofed up the pre wired inputs so I have to figure out all the voltages to get the screen back up and running. Does anyone know what the actual input voltage to the controller board is? I am using the New verge lcd, it looks to be the exact same board as the PSONE 5" unit.
JR
Yea, that is pretty much my thoughts. I have it figured out I think. I am gonna play some more over the weekend and see what I can get working. It is gonna be close though lol
I goofed up the pre wired inputs so I have to figure out all the voltages to get the screen back up and running. Does anyone know what the actual input voltage to the controller board is? I am using the New verge lcd, it looks to be the exact same board as the PSONE 5" unit.
JR
moving CRT lens away from the LCD
I wonder if you could put a piece of 1/4 inch plate glass between the LCD and the CRT projection lens, to move the lens out by 1/4 inch? I think that will stretch the lens focal length by almost the whole 1/4 inch.
I know it isn't much, but if it's all you need to make it fit...
Another way to stretch a lens focal length, is to use a negative lens. Has anybody tried that with a CRT projection lens?
I wonder if you could put a piece of 1/4 inch plate glass between the LCD and the CRT projection lens, to move the lens out by 1/4 inch? I think that will stretch the lens focal length by almost the whole 1/4 inch.
I know it isn't much, but if it's all you need to make it fit...
Another way to stretch a lens focal length, is to use a negative lens. Has anybody tried that with a CRT projection lens?
Well I just tried putting a plano-concave lens, about 90mm diameter up to a ~100mm diameter crt lens, projecting a 5" blacknwhite portable tv, and yes, it increased the focal lenght plently (perhaps about 1.5-2 times!) but had less brightness/contrast/sharpness... didnt like it!🙂
negative lens
I think it would work better with a very weak negative lens: Maybe with a focal length of 1000 mm or so. That could increase the back focal length enough to get it off the LCD, without distorting the projected image much.
But with a small image source like a 5" TV or LCD, you can project very nice images with a simple PCX or positive meniscus lens. You only need triplets or better to make images with bigger field angles.
Just get one with a long focal length, so the angle of the image field is 20 degrees or less and it should be fine. To make it brighter, use an upper fresnel to converge the light into the lens.
I think it would work better with a very weak negative lens: Maybe with a focal length of 1000 mm or so. That could increase the back focal length enough to get it off the LCD, without distorting the projected image much.
But with a small image source like a 5" TV or LCD, you can project very nice images with a simple PCX or positive meniscus lens. You only need triplets or better to make images with bigger field angles.
Just get one with a long focal length, so the angle of the image field is 20 degrees or less and it should be fine. To make it brighter, use an upper fresnel to converge the light into the lens.
about using a pcx or pmn lens for a 5" source - no-no! It wont focus center/edges properly, especialy PCX (tested PCX with a 5" tv my self). And it will have bad light abreviations, the haloey effect... Triplets all the way!!! (maybe doublets too...)
Got it linedup!
Ok, I got the CRT lense to fit. I mounted it and started testing different light sources. I think this is truely going to be the largest challenge of a projector like this.
The reason I say this is because of the efficiency of the set up and the short focal lengths...It seems to me you have to have an absolutely evenly distributed light source across the lcd or it hotspots real bad. I think a VERY bright backlight of some sort is going to be the best bet for picture quality I tested a little with some small pieces of frosted plastic and frenzels to see if it would work to put a couple of cf's 65k behind them. I dunno. I think it may work but it is going to be very low lumen. I will play more, but I really wanted to be able get away from using an expensive light source. I am looking to get maybe 100-200 lumens ANSI. I dunno.
TBC....
Ok, I got the CRT lense to fit. I mounted it and started testing different light sources. I think this is truely going to be the largest challenge of a projector like this.
The reason I say this is because of the efficiency of the set up and the short focal lengths...It seems to me you have to have an absolutely evenly distributed light source across the lcd or it hotspots real bad. I think a VERY bright backlight of some sort is going to be the best bet for picture quality I tested a little with some small pieces of frosted plastic and frenzels to see if it would work to put a couple of cf's 65k behind them. I dunno. I think it may work but it is going to be very low lumen. I will play more, but I really wanted to be able get away from using an expensive light source. I am looking to get maybe 100-200 lumens ANSI. I dunno.
TBC....
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