Have you ever flashed your friends?

...with a flashlight (torch) that is.

Anyway, I guess it eventually comes back at you. I was in a lecture theatre chatting, and somehow playing with an overhead projector. And as I was looking down the top lens (the small little lens above the document that the light passes through before going onto the wall), my friend turned it on. Not that he did it on purpose, and it was only a flash because he realized that I was there and turned it off quickly. I must say though, boy was it bright.

And after that I opened the cover to see the innards (don't ask why, I just like to take things apart). The filament in the bulb was still glowing orange and slowly cooling down. Anyone know how many watts overhead projectors are generally?

New idea, why not just carry around an overhead projector with a backpack battery to have a very bright light that gives out near perfect circle of light. Anyway...

YC

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by yclo:
The filament in the bulb was still glowing orange and slowly cooling down. Anyone know how many watts overhead projectors are generally?<HR></BLOCKQUOTE>

The ones I've used and stomped on (think Beavis & Butthead videos) ran around 1.0 to 1.2KW, not including the fan. The bulbs are quite surprisingly bright if you aren't expecting to get blasted.

Friends?

Typical overhead projectors here run the lamp through an internal transformer, at about 24v AC. Usually no more than 250 watts, bipin halogen lamp capsule, incredably bright indeed but no way transportable unless you like carrying two 17Ah lead acid batteries around with you!

The very first kind that did not use transparent film, but instead shone a powerful lamp on white paper with some sort of reflective surface behind, often ran to over 1000 watts (at mains voltages), but they are highly uncommon now and I have only ever seen one to this day.