| DaViruz |
Hi.
Iv'e been browsing around some threads now, but something io cant find is pictures of how the projections look. :-) If anyone have a link or pic, please post it.
Iv'e been playing around with this even before i saw this forum (which was like an hour ago), i used a CCFL-backlit 2.5" color LCD (only 160x146 px though), and in a totally dark room i could project a great image on the roof (about 1m). I will try this with a better light source as soon i have money to purchase one :-) |
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| noodles |
There wer tons of pics on the old thread we had. But someone shut it down.
You can check out some pics at cowan's site at www.diyprojectors.com
Welcome to the DIY projection scene! |
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| SuperZoboo |
| and you can check out pics of our project here. also, links to some great projects (better than ours) at Marklar and Undreams site (links on my links page). |
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| cowanrg |
well, working on site update now. gonna have like 10mb worth of new pictures for contributors...
hopefully tomorrow i will be finished. its really cool that more people are getting interested in this. |
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| Duo |
What's your guys' usual largest screen size?
I made a projector out of a regular tv that gives me an image
that is clear, bright and sharp and is 150" diagonal. I barely had enough room in the audio room to install the screen, which I made myself.
Right now, I'm thinking of making an lcd projector instead to see how much better it is. I'll use a 400W metal halide and fresnel lens and glass projector lens for the idea... |
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| jvisaria |
Duo,
Do you have a web page? Your homemade CRT projector sounds interesting ... it isnt the one with a TV and fresnel is it?
Please give is some details. |
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| Duo |
Yes, actually, mine is the one with a tv and fresnel... I'm into electronics so I altered my tv to go brighter and reverse it's own picture(both very trivial and elementary in electronics) And I simply made a cardboard projection box and painted it black (pun intended if you know the rolling stones) and used an 11X8 fresnel
which I got at staples office supply... It gives a very impressive picture since you can read some small print and also easily play nintendo on there, which is cool cause when the screen is the the wall, (the complete wall) you feel extremely immersed in the game, like you could walk into it. Also, I made a special surround system so you really are "in" the game;) It's awesome for movies too, my sound is better than that at most theatres to it's a much nicer experience. |
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| xblocker |
Duo,
hey, my first projector was same type, but the brightness was very poor on a white wall, but with a curved aluminized screen fairly good. I didn't use a fresnel, but a huge (140mm dia.)plastic triplet objective, which was very expensive.
xblocker |
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| Duo |
| I find that you need bigger than 140 mm by quite a bit to have acceptable brightness. Though, I also know how to modify a television to go brighter than normal... Getting good brightness is extremely tricky with that kind of projector, you need a very dark box inside and it can't reflect any light at all (which will blurr the picture and cause chromatic problems) and the box has to be very solid(no holes or slits)... I tinkered with the thing for a year just to figure out how to make it work properly and I did pretty good, but I figure an LCD projector with 400w metal halide would just be better! |
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| jizmmunki |
Hi, there were pictures of the image and designs (very simple ones) of the fresnel based projector you talk about above at www.diyprojectiontv.tk
ive made one and am very happy with the image (and the price) but the pic is a bit blurry around the edges, any one know how to sort this, and where is a good place to get ridged fresnels from, as the site only sells floppy ones,a ndi feel that may be the prob.
any sites with other plans, or more detailed plans would be greatfull recieved! email... jizmmunki@hotmai.com |
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| Duo |
Hello jizmmunki;
I read in other threads that you need to add extra lenses to the
projector to make the edges focus. Say your fresnel has a focal
length of "x" then if you want two lenses, they each have to have a focal length of x/2 where each lens is half the focal length
of the desired total focal length.... |
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| xblocker |
No, each lens has to have 2x to get a total FL of x. (1/f=1/f1+1/f2)
xblocker |
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| Duo |
Dangit, I knew I wasn't thinkin straight! Xblocker is right.
Darn I always get screwed up with things that involve adding reciprocals! Same as resistors in parallel in electronics (1/total=1/r1+1/r2+1/r3+etc) I used to always screw that up too! |
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| cm961 |
Hey Duo,
how did you modify your tv to make it brighter and reversed?
Pete |
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| Duo |
| Well, I did two special thing to the television to make it reverse and go brigher. First, to reverse the picture properly, I had to make the tv scan backwards, this was done by reversing the horizontal wires to the yoke thus putting the signal 180 degrees out of phase. Then, to make it brighter, I cranked the contrast circuitry and the plate voltage on the tube and made a couple of adjustments to the circuit. I don't remember exactly what i did to the circuit to make it better, but it was to improve the contrast performance of the tv so I wouldn't get black splotching. These to changes made it so I could operate with the tv rightside up. Also, it gave very good brightness. |
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| eebasist |
Duo:
You might want to add that playing with the inside of a TV unless you are properly trained, or take appropriate precautions, can easily be lethal with the extremely high voltages present. |
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| Duo |
eebasist: I might want to add that I would expect most people here to already know that, also, I might add that: If I were you, I wouldn't tell me to add!
Dictionary Implications:
Play: To occupy oneself in amusement, sport, or other recreation;
something a child does simply to do so not intending result of any specific consequence or reason.
Work: Physical or mental activity directed toward the production or accomplishment of something; A person with direct intentions
and a will to practice his doings for a specific result without mistake, if possible.
After this, I may state: One should not work with such units pertaining to or operating by use of high voltages unless oneself is satisfactorily educated in such a field.
I may also state: I was not asked to explain how to alter the normal effect of a television set, I was inquired upon as to how I would do it. I did not imply that one should simply go ahead and do it and I believe that one would only desire to perform such a function under educated circumstances anyway. |
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| eebasist |
| Actually you'd be suprised.......when you expect people to know something that we take for granted. This is a DIY forum, but not everyone here plays on the same level. I just wanted to add to your statement that you need to know how to play with the inside of a TV before you do it. |
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| Duo |
| okay I get your point, but our intentions aren't to "play" with the tv, they are to work on it. I do think people should know that tv insides can be dangerous, but since most people here are adults and lots deal with electronics, most would know that tv's use high voltages or can read the warnings on the tv though, I don't expect them to. Also, I wouldn't generally reccomend that people work on their tv sets unless they know what they are doing. Simply stated, someone asked me what lengths I had to go to to change the tv and I briefly explained how I did it. ;) |
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| eebasist |
| I'm not trying to argue with you. I just want to emphasize to anyone naive that the insides of a TV can be very very dangerous. Only reason I am saying this is I know of an local repair person who got shocked very very badly......luckily he was accross the street from a good ER with people in the room adjacent to the accident |
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| cm961 |
Thanks a lot Duo,
I have yet to make the modifications, because I'm having trouble with the 'projector' end of my projector. But I will "play" around with it a bit... And I'm not too worried about blowing myself up, the TV I'm modifying should be simple enough, and I like to pretend I know what I'm doing (I'm supposed to be an electrical engineer). I've got a million projects on the go right now, so I don't know when I'll have time to finish this one off. So far so good however, but my image is a little blurry :mad:
Thanks again for the info!
cm961 |
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| remp |
Duo
EEBASIST was quite correct in posting his comments suggesting people be careful regarding safety with television sets.
Tv sets do have dangerous voltages inside which can kill and a further point which may not be well understood is many TV sets today do not have a mains power transformer but are connected directly to the household mains power so in some circumstances even taking the back off to have a look inside can result in touching the potentially live chassis with lethal results.
That is why TV service persons use an isolating transformer when servicing TV sets.
As DIY people we may know ourselves some of the dangers but who is to say someone reading this information, with little or no electrical knowledge may think a certain proceedure is safe when in fact it is not. |
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| SushiMasterX |
Snagged it off of Ebay. $150 reserve, $325 buy it now. 4 days left. Sharp QA-2500 at Ebay
The picture (from JAY JAY THE JET PLANE. Aww, isn't it cute:rolleyes: ): |
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| jrees |
is there anyone out there in the UK willing to sell me a moidified tv (inverted picture, very bright) so i can use it as a projector?
thanks
john
and where can i get glass cut to surround my fresnel lens |
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| White Knight |
Duo:
Could you tell me what you built your projector screen out of:confused: am starting to build my projector monday, w/ 130" possible screen size, so I am looking for a nice projector screen!
:) :)
Thanks,
White Knight |
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| White Knight |
Nexzus:
Thanks Man, that really helps, because the 16:9 screens are $1000 in USA also!
Thanks again,
White Knight
:D :D :D :D :D :D :D |
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| annex666 |
| quote: | Originally posted by Duo
They forgot the decimal when they came up with 56K!!!
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Sorry to let you down, but Kbps stands for kilobits per second, not kilobytes per second as is often thought.
There are 8 bits per byte (as of course we all know) so therefore your 56Kbps modem works out at around 56.6k/8 = 7.12K and you can't forget that most connections rely on a parity bit so that drops to 7/8ths useful bandwidth - this makes the theoretical maximum data flow rate of about 6.2K (which is rarely achieved).
Hope this clears up your apparent confusion. |
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| Tinker |
| And thats only with a perfect 56k connection which totally doesnt exist. Ping rates are low and that makes it seem worse. Add to that the fastest that most of us poor dial upers get about 49k-53k I 've seen low as 33k on a 56k modem cause the main lines (at phone poll) were so old and crappy. Yes I did everything you could (besides tell him to move), wasnt windows, modem drivers or house phone line-streight out best was 33k even with a line filter! The suburbs can kill......So he's talking about a therietical maximum. A realistic figure would be even lower than that! I would figure about 5k maybe. Just wanted to put that in perspective.:D |
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| remp |
Tinker
These last two posts seem to have drifted in here from somewhere else. We try and get that fixed but in the meantime what you say about modem connections is mighty interesting.
In my home town we have old old cables always giving troubles mostly to computers. Not so much for audio but I had a phone man around today checking the line for noise. He said its a standard problem virtually unfixable until they do some recabling because all the good lines have been taken.
That line filter you mentioned. Could you give us a few more details. I would really like to get the most speed out of the modem as humanly possible so any tips would be great.
I have an optima 336 modem
Thanx |
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| Tinker |
Well I'm from US so, dont know what is available in your specific area. But Radio-shack has them, so does staples I believe. I can search on the .net again for the plans I found for them also. Truely the DIY route. The guy who drafted up the plans says it also helps when a fax or answering machine shares the same line aswell.
Heres a DSL filter but will work for Dial up modems aswell. What it does it cuts out interfearence from cordless phones and other household devices.
"Z-200SM Single-Line Filter (in-line)
In-line Z-BLOCKER® filter for single-line phones or telephone equipment
Blocks interference between voice and DSL/HPN
Ideal for blocking RF interference from cordless phones and other sources
Works with any single line phone, fax machine or dial-up modem
Plugs into any standard phone jack "
Here: http://www.excelsus-store.com/searc...asp?search_id=1
The DIY one was somewhat different though. I'll have to look for that again!
This is more like the ones I have used
: http://www.ky-filters.com/
Thisens for Euro countries:
http://www.walkabouttravelgear.com/filter.htm
"Tax impulsing is connection-disrupting noise pulse found in Austria , Belgium , Czech Republic , Germany, Slovakia , Spain , and Switzerland . Tax impulsing is used in these European countries to monitor the length of telephone calls for billing purposes. Invented before modems, tax-impulsing (or metering pulses) can cause data errors or even disconnects. All our tax impulse products work with a RJ-11 phone jack (North American style) and modem adapters may be needed in other countries.
Modem Saver International
A feature-packed item which alleviates three of the major concerns when traveling with a modem: tax impulsing, digital phone lines, and phone line surges. Not only a tax-impulse filter but also a digital line tester which checks for the presence of digital lines which can fry your modem. Also a phone-line surge protector. Includes special adapters for checking and reversing polarity, and a compact nylon travel pouch. Small and lightweight, with a 1 year manufacturer's guarantee. 100% line powered; no batteries required.
#22SAVE $58.00"
Hope that helped, see what else I can find for you...
P.S. I thought that was weird, allasudden were talking modems out of the blue, I just jumped in cause pc's are my thing.
;) |
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| remp |
Tinker
Thanks a lot. very helpful.
Did you spot Multiplexor's thread about getting a small fast boot pc to drive his car LCD. |
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| Tinker |
| No I didnt see that, I'll have to check it out!:D |
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| Duo |
It seems some people wanted to know what I use as a screen.
I usually use a large white wall(if I have one in my house).
Otherwise, I use a thing call foamcore, which picture framers use.
The stuff I have comes in large sheets which I think are around 40" X 30" or something. I used six of them on my last screen. They work very well. |
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| Kim Turley |
| check out my site below for some pictures |
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