| mccamp82 |
I was wondering if there are basic distances people use between the bulb and the fresnel. and also the distance between the second fresnel and the projection lens. I have searched everything i could think of to find this and i can't find it anywhere. Is it more of a trial and error thing that differs for each projector, or is there a basic measurement. If it helps, i am using the diylabs triplet, one of their split fresnels, and a 400 watt bulb.
Thanks |
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| moi |
dist between bulb and fresnel= fresnel fl
dist between 2nd fresnel and proj. lens =proj lens fl
am i right? |
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| cruser |
place your bulb 8.9" from the rear fresnel
then place your triplet 12" from the front fresnel if you have a 2" space between the front fresnel and lcd
if you have less than 2" just add the difference to the 12"
the front fresnel has a fl of 13" but 12" floods the lens with light
and thats what you want
just use trial and error to find the best placement for the front fresnel rember to try to send as much light as you can thru the triplet with out cutting off the corners
do you plan having an adjuster for your triplet? |
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| mccamp82 |
I have tried thinking of way to have an adjuster, but right now, since this is my first DIY projector, i'll just stick with a fixed triplet. I have pretty much everything figured out, and am about ready to get started, but i just didnt know those things. I also don't know much about switches, but I am sure that isn't too hard tofigure out. Thank you very much for the info. I will start there. I am going to have the front fresnel 2" from the LCD. I learned that from you cruser, actually.
One more question....
What are the dimensions of a stripped 15" monitor? Is is smaller than the 12.2"x12.2" fresnel?
I gues that's all for now. |
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| vudutek |
| quote: | Originally posted by cruser
place your bulb 8.9" from the rear fresnel
<snip> |
this may seem like a dumb one, but i'll ask anyways...
the 8.9 between bulb and rear fresnel: is that from the bulb itself, or approximated from the filament to the fresnel? i ask because i'm using one of the big 400 MH bulbs, and want to have it positioned right the first time.
thanks,
greg |
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| cruser |
| quote: | Originally posted by mccamp82
One more question....
What are the dimensions of a stripped 15" monitor? Is is smaller than the 12.2"x12.2" fresnel?
I gues that's all for now. |
the active area on a 15" lcd is 12"x9"
the actual glass varies in size from lcd to lcd
that 12.2" fresnel is not large enough to display the entire 15" lcd
close but no cigar you will have to resize the display to get the whole image on the screen
| quote: | Originally posted by vudutek
this may seem like a dumb one, but i'll ask anyways...
the 8.9 between bulb and rear fresnel: is that from the bulb itself, or approximated from the filament to the fresnel? i ask because i'm using one of the big 400 MH bulbs, and want to have it positioned right the first time.
thanks,
greg |
from the arc/filament |
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| mccamp82 |
Cruser,
Thank you very much for the help.
I ran to circuit city today. I almost bought the Liquid Video version of the cmvm 1515, but decided to wait after I saw the warranty was only 3 months. So instead I went to Sam's Club to check out their selection of LCDs. The had an NEC 1512 for 269 bucks. Anyone know if this is a good monitor to strip? I also saw an lcd monito that is HDTV ready, has all inputs including Component, S-vid, and VGA. It is 16:9, but is pretty small. No bigger than a 15", just maybe a little wider. Anyone think it is possible to make a projector out of it? Are there any fresnels big enough for it? Here is the link http://www.samsclub.com/eclub/main_...fcfkjdgoodflh.0
Also, can someone explain how you hook of the switches for a projector? I know you need one for the bulb, one for the fans, and one for the LCD. Do you wire the switches in series or parallel? Where can you get switches? Radio shack? Maybe if someone has a diagram of how to wire them it would help a lot.
Thanks again everyone.
Later |
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| mccamp82 |
another question...
Since the fresnel is a square and the lcd is rectangular, does that mean you have to cut the fresnel down to the right size (i.e. 12x9) ? If so, how you you cut it? Also, I have seen people, including cruser, who cut grooves in to the mdf that hold the fresnels and lcd. If you do this, does the light shine throught the angled corners of the fresnel? I guess what i would like is a picture of someone's fresnel so I can compare it to the shape and size of the diylabs fresnel. Does that make any sense?
Thanks a lot. I am sure i will continue to have more questions and appreciate any help i can get.
Later |
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| cruser |
yes i cut the fresnel into a rectangle 11 7/8" X9.25" and inserted
the 2 sides that are 9.25" into 1/8th " deep grooves the other 2 sides but up against the lcd frame atleast thats the way i do it
heres a few pix of the prosess i use a router table to split and cut to size
this is a diylabs 12.2" fresnel |
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| cruser |
| after routering the edges pull the 2 pieces apart |
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| cruser |
| and mounted into the lcd frame sandwitched between glass |
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| EasyPrey |
| quote: | Originally posted by mccamp82
Cruser,
Thank you very much for the help.
Also, can someone explain how you hook of the switches for a projector? I know you need one for the bulb, one for the fans, and one for the LCD. Do you wire the switches in series or parallel? |
I'm not sure if we are talking about same 'switches' but from my knowledge regular onn/off switch should look like
OFF:
line 1 ______ \______
line 2 _____________
ON:
line 1 ______ ______
line 2 _____________
I beleive it doesn't matter wich line will be disconnected (in europe at least)
Placing two switches in whatever cfg will require them both to be on to let electric current flow. They usually have two/three switches for nuclear rockets :) |
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| Mr.Kh |
Cruser, so are you using a router bit with a profile as such(kinda like a cutting wheel):
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and removing some material between then front and back? Or are you just removing the complete glued edge of one side (like the back might now have overall dimensions .25" less)? |
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| cruser |
| i remove the complete glued edge there are no rings there anyways and it comes out razor sharp,perfect edge |
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| mccamp82 |
Here's another quesion....
If i use a condensor lens, would i put the fresnel 8.9" from the condensor or just the bulb filament? |
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| jcbklyny |
| When using a condenser you would measure out your focal length to the top of the condenser lens... and not the filament of the bulb. |
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| mccamp82 |
| Thanks, jcbklyny. |
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