Big rainbow

We used to use an old slide projector and a prism to create a largish spectrum on the wall. The bulb blew and all the replacements seem to have a different construction because they have a green gap.

Ray boxes work but are too small and faint.

We still have an OHP - can I do it with that somehow? Not quite sure where I’d need to put the prism.

Or suggestions for what else we could do.
 
We used to use an old slide projector and a prism to create a largish spectrum on the wall. The bulb blew and all the replacements seem to have a different construction because they have a green gap.

Ray boxes work but are too small and faint.

We still have an OHP - can I do it with that somehow? Not quite sure where I’d need to put the prism.

Or suggestions for what else we could do.
Put the prism on the OHP as the light comes from the bottom and see if you can get the scatter to go through the viewer and show up on the wall/ board
 
Make an card mask with a slit cut out of it 5mm x 50mm to cover the OHP Plate. Hold the 60 degree prism, point downwards, just in front of the slit. You should get spectrum on ceiling. With a bit of fiddling you can get it on the wall. You don't need the top reflector of the OHP, cover it or block it. Just did it!
 

karen b

COMMITTEE
We used to use an old slide projector and a prism to create a largish spectrum on the wall. The bulb blew and all the replacements seem to have a different construction because they have a green gap.

Or suggestions for what else we could do.
we have a stock of old projector bulbs. I don’t mind popping one in the post if we have the right size. It might work for you. Not even sure if we have our slide projector any more
 

Nick Mitchener

COMMITTEE
I used a slide projector and a spherical flask to make a single raindrop rainbow. I don't see why that would not work with an OHP. You need to collimate the light source, that's all.
 
we have a stock of old projector bulbs. I don’t mind popping one in the post if we have the right size. It might work for you. Not even sure if we have our slide projector any more

This is the replacement that doesn’t work. It’s 24V 250W. It’s fine for slides but we don’t have any to show anymore
 
Ha, this is confusing, I thought it didn't work because it had blown. Technician Q, have you got a picture of the blown one that you're trying to replace? :)
 
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