DIY Video Projector Part II

[tomithy83]

in most eceltric apps it wont hurt if the ground is not connected its just a precaution

should be fine but im no electrical Engineer

[Duo]

Sorry to but in on you guys, but what do you consider to be a really BIG size for a projection screen?? Mine is 7' tall and 9' wide, hows that for a screen??

[djquick_silver]

I was looking through links on this site the other day and ran across one of them that said that the ground (green wire) should be hooked up to the ballast casing i wish i could remember what the link was but since i've been doing so much reading lately it's buried somewhere... all i remember is that it had something to do with Icecap?? ballasts for MH bulbs ... hopefully this helps or maybe youi could find the link again they had a full wiring diagram for MH bulbs and ballasts.

[daveb]

In digging around the web, I see references that both the reflector and the Ballast base should be grounded.
So far, I haven't got a reflector, so the base seems to have been a good guess.

If anyone is in the know, I hope the knowledge will out. There seems to be some advantage to grounding aside from safety. I've seen reference to the fact that is takes out some interference; I wonder if it'll cut down on the hum that the ballast makes.

Probably not...

dave.

[the whinner]

hy, i am new here and i need help from german DIY-ers!
can some of you tel me what is the german word for page magnifier lens / fresnel lens ( 8 x 11 inch or bigger )!
i live in Yugoslavia and there is no way to find fresnels here, but i have some friends in Stutgart, Germany and in Wienna, Austria, who could buy them for me!
the only problem is that i dont know what are they caled in german!
or can you give me some links or adresses in those towns, so i could tell them where to go!
THANKS!!!

P.S.: you might find this link useful!

http://www.physics.umd.edu/deptinfo/...cdem/l7-33.htm

[biteon]

pink line is the air

air gose in through the fans than it gose through the tubes than air gose through the side holes in the mirror reflector i made than out the front of the reflector (holes) than hits the low-e glass then comes back to the light and out the hole where the light is going in to the reflector then the air gose out the exsost hole.
sorry for the run on sentance.

like this your not circulating hot air,or messing up the reflector, and its cooling the reflector, glass,and the bulb. i hvent tested it because i need to mount the bulb and order the low-e glass to finish my projector.so im still not positive this will work, but it sounds to me like it just might.

yelllow line is the light

this is what im hopping will work,or else im back to step #1. as long as the light gose some what forward and there is a fresnel right at the end of the reflector to catch all the light coming out of the reflector than the fresnel will send the light in one direction. i think it just might work see my picture. if you guys see a problem or have a queston, just tell me .it would help me out.
thanks & later.

[Duo]

looks like a great idea to me, that's exactly what I plan to do!
I hope a 400w halide produces enough lumens, I know it's sure darn bright in the open room as it is!!!

[MikeZupcak]

Biteon, i saw your diagram and have a few questions:

Where did you buy your bulb? What size and model LCD are you using and what are the blue lines and the green line in front of the light.

[woneill]

MikeZupcak,

Re your 7" 16:9 screen idea.

1) Check out whether the pixel res is RGB triplets horizontally, or each LCD shutter (one each for R, G and B). Most small video panels are quoted with a shutter res, and must have their horizontal resolution divided by three to get a reasistic figure.

2) If it has the correct resolution, then you could probably use a higher quality fresnel as an intermediate collector lens between the panel and the main objective, or go the OHP route.

Either way, you need to get all the light coming through the panel to go through the main objective in a controlled manner - otherwise you will lose brightness and/or quality.

The best bet is to use an objective lens that is bigger than the LCD panel - but there are very few 7" objectives around (the fresnel arrangement is a compromise on this). You COULD explore the route of using a 5" panel with the same type of 5 7/8" PCX used by Undream...

Bill.

[biteon]

the 2 green lines is the low-e glass which is two pieces of glass and some sort of gas in between to filter hot air . i desided that it might separated the box in two parts 1 the hot stuff side with the light and any thing else that can withstand alot of het and 2 the side that can not have to much heat forinstants plastic fresnels and controler boards and lcd polarizers etc. . but if the cool side of the separration is still to hot im planning to put a small fan.

the blue lines are the two fresnel lenses(plastic for now)one to capture all the light from the reflector and the other to condence the light so most the light is on the lcd and not all over the box walls being wasted.

the lighter color yellow after the low-e glass is colder light sence its being filtered from the low-e glass. and the box under the fresnel lenses is a metal box i made to cover and help keep the lcd controler chip cool i had a (heat problem there not to long ago),it also make it easy to separrate the box more with the fresnel lenses and wood.

im using a 5.6" car lcd color with remote and it has 700x900about res. and bought it at e-bay from some company name starvision for about $124. with out shipping etc. . the bulb is a 400watt metal halide ms400/u i think and i bought it here in my home town at a electrical store called "electrical distributers" or something like that. ive been having cammra problems so its been hard to get pictures ,ive been drawing most of my work.