Hi everyone,

I have aquired about 8 or 9 older overhead projectors. Four of them are the same make model ect...

The fans that are in these are pretty quiet. I'll try and attach a picture of one running on my work bench.

My question is this - Will they pull enough CFM's to keep the box cool? I have designed my box to accept two of them.

Also are all fresnel's the same? I mean are the old ones out of the OHP's as good as the ones from the store (Lumenlab).

You guys can comment I wont bite.

Here is what I have put togeather so far.

Don't know about the fan but I'd get new lenses if I were you. Box looks good.

Skeeter,
I would probably say that you are safe with both of those fans...especially since they are mounted at the top, since hot air rises

As for the lenses...check the focal length on them. If this matches and the lenses are the right size, covers the area of the LCD screen you are using, I would say that it would be safe to use them.

However, the odds of them matching the focal length of the lenses we are using, bought new, are very slim which means that all of your measurements will be different then what everyone else is using.

Hope this helps.

Also box looks good so far. You might have to fight with all of the light that is going to try to shine through those holes though.

My concern is that you want the lenses as optically perfect as possible.

Sorry if I sounded like he shouldn't take your advice Brainchild I was just thinking that if he had nine projectors then hopefully one of them would have a quality fresnel.

Then if the those fresnels don't work out, focal length problems etc then BC has then ones that the large majority of us are using and it will only set you back $33.99 plus shipping. It's located off Lumenlabs main page under the Store link.

Thanx guys for resonding.

I haven't got a lot of cash right now, I just spent all of my "She Don't" money on a BenQ 567s monitor for the projector.

I will have to use the frensels that I have until I can afford new ones. I also messed up my 320mm triplet. Note* Do not store the triplet uncovered near the grinder where you sharpen lawnmower blades! I'm a Duh

The triplet now has nice little pecks on it. Well it will work for testing.

"She Don't" money is cash that she don't know about therefor she can't take it away!

This box is just a test box. I made it from the guide I bought here. When i get all the kinks worked out I will make a better looking one.

I've got an idea for the light leak from the fans. I will post a picture when I get it installed. Just got the light set in straight last night.

man sorry to hear about your lens.

can you measure your fresnel focal lenth?

Hi joe,

Yes I think I can measure the focal by holding the frensel close to the ground and start backing it up until I get a point, then hold it there and measure the distance.

The old OHP frensels appear to be in very good shape - straight flat, not scratched.

How big square or rectangle should I cut them for a 15" LCD?

Is the glass that is on the deck of an OHP "tempered"? If so I've got plenty to mount the frensels to.

I have all of the top lenses from the OHP's (the ones on the head that adjusts)
If any one can find a use for them I'll be glad to share. I'll post a picture later today.

Thankx again every one

12" x 9.75"

The glass is tempered.

Thankx Brain,

I'll start cutting tonight.

Here is a pict of the OHP lenes and arms.

Let me know if they are of any use to anyone.

Singlet lens bad.

So I guess they need to go into the "round file"?

Heres one I took out just to experiment with.