Advice On OHP To Use With Panel In Classroom

[teacher]

My school has an old lcd panel that I'd like to use in the classroom. The problem is that our ohps are underpowered 3m things. When I set the panel on the ohp -- even in a semi dark room, it is very hard to see (near impossible).

So I'm going to spend my own money to buy one on ebay. How many lumens would you recommend I get for a semi dark classroom (light comes in the upper windows from the hall; at least one flourescent has to remain on so they can see to write; but the front of the room is reasonably dark.) I have seen some decently priced ones at 4,000 lumens, which is about twice what our current projectors put out.

The cost of replacement bulbs also is a factor, since I'll have to supply those, too.

Thanks in advance!!

[randini]

Hello,

Two things came to mind when I read your post.

1. Do a lamp Modification on your current overhead (like the much talked about metal halides). Requires buying a bulb, ballast, and mounting the bulb, doing some wiring. May have to add a cooling fan. The metal halide boast 20,000 lumens with ~15,000 hours life for the bulb.

2. Check locally for overheads. I live in the GR area, and I found a 3M with triplet lens, front side mirrors, 4000 lumen setup for $30. Comprenew had gotten this from a local school who recycled their equipment with them. Save yourself some money. My replacement bulbs were $8 each and they say 100 hours for the "-5" series or 40 hours for the standard, but who really knows

The OHP that I have works ok dim lighting, but I haven't spent enough time critiqing it yet. I am using a laptop LCD mounted on it. Wish I had more results from my setup.

/2and

[snortonnorton]

Dukane starfire 4003.

i bought a mint one for 50 bucks on ebay cause ohp's are obsolete now, the universities have their own dedicated lcd projectors on ceilings so you can get em cheap.

[Guy Grotke]

Image brightness falls at the square of the distance. if you can move the projector closer to get a smaller image, it will be brighter.

A lot of OHPs on eBay are from school surplus sales. Maybe you can ask your district equipment warehouse if they have any better ones. Or ask some other nearby districts if they have any for sale. Usually pennies on the dollar.

Or maybe you have some businesses in the area you could ask. Most businesses that used OHPs have switched to LCD projectors and they may have an old OHP or two gathering dust.

Or try asking for a donation on Craig's list... Lots of folks love to find a new home for their old stuff, because they feel bad about junking working equipment.