[rollei_list] Re: Rollei Projectors
- From: Don Williams <dwilli10@xxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 28 Jun 2013 11:31:42 -0500
At 02:48 AM 6/28/2013, you wrote:
Thanks, Dirk and Carlos, for the information and the projector website.
I would be interested in the P11 upgrade if it makes sense. That
website has not changed in years so is probably no longer
supported. However I saw someone selling a P11 with Halogen bulb on
EBAY only recently.
Need to have my "new" 220 V P11 overhauled anyway. But, I will stay
with the old bulbs and the extra heat filter if there are major
disadvantages to the halogen upgrade (uneven light distribution?).
Would also be interested in a good deal on a Rollei Twin for my
(3000+) 35mm slides.
Jan
I realize this would impractical for most folks and now it would be
impractical for me.
In my active engineering days-I would design an LED replacement for
the halogen bulb, based on some specific CREE LEDs. Cree did send me
samples of a new chip and I powered one up with some D-cell
batteries. The light output was dazzling!
I have, in days gone by, designed some relatively complex power
conversion systems, and unrelated to that, designed a surveying
distance measuring system that used an IR LED for the transmitter.
We now know that CREE, and many other companies, have developed
integrated circuit current controllers that fit into the base of
their newer incandescent lamp replacements. No longer having access
to a lab this is not something I would undertake now. Some day, when
the bulb on my B&L Balomatic 755 projector goes out, I will have to
either find a replacement bulb or donate the projector to someone who
wants to deal with the problem.
For folks not familiar with this projector, I find it to be superb
for MF slides, most of which I have glass-mounted. It uses
cassettes, has automatic and manual advance and reverse, a single
button remote that can also command reverse, a means of ejecting a
slide from the viewing area, and has excellent optics. I got it over
30 years ago from a store back East, on sale, because the "self
timer" feature was failing on that model. It turned to be a rubber
pad that managed an air-flow timer, had fallen off. New glue fixed
it and it has been reliable ever since.
On a related topic, I believe the LA street department is up to about
48,000 LED replacement units for street lighting. Their program paid
for itself in replacement and labor within the first year. They
simply install a new LED unit (includes mount and reflector unit,
designed for simple plug-in installation) whenever a bulb fails. The
color performance of the LED section is specified in great detail.
Now for the bottom line- I don't know whether an LED combination can
be designed to replicate the color features of a hot filament,
perhaps we will someday know.
DAW
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