P3D Re: Halogen bulbs for projectors

[Tom Hubin <thubin@xxxxxxxxx>]

> Dalia wrote:
> 
> Tom, I'm surprised that you didn't use a 500w halogen in the experiment
> with the 500w incandescent. Using a 750w halogen may raise more issues than
> you would want.  

Actually, it did not start out to be an experiment. One of the club's
two modified TDC116s was melting slides. The other seemed to be ok. I
volunteered to investigate. 

Both had been modified from CZX 500W lamps to BTP 750W Halogen lamps.
Both had beefed up fans for extra cooling. As it turned out, one was
equipped with a better heat absorbing glass than the other. As a result,
one sometimes melted slides and the other did not, although the slides
did get very hot. 

Anyway, in the process of the investigation I determined that, to add
insult to injury, the BTP 750W lamps produced a dimmer image than the
original CZX 500W lamps. Being naturally inquisitive, I just had to know
how this was possible. That is when I found out how the filament size
can effect the projected throughput.

I recommended that a 500W halogen replacement for the CZX would be safe,
maybe brighter but not much, and likely cheaper over the lifetime. But I
had no luck finding one and neither did anybody else. I will mention
your 500W halogen replacement to PSSP, the owner of the projectors.  

> Why don't you just order a bulb from us and do some experimenting. 

I'd like to do that. I don't own a projector but PSSP still owns two. I
have one of them here. I'll see what the club wants me to do.

Tom Hubin
thubin@xxxxxxxxx