Date: Tue, 5 Apr 2011 16:58:16 -

Author: --- "Rueckner, Wolf"

Subject: Re: Spectral lamp positioning?


Correct, Urs. The socket should be at the bottom. These spectral lamps all have different current ratings and therefore each lamp needs a slightly different exciting voltage (or current limiter). It sounds like you're running it with too much current and that's why it's getting hotter than expected. -- Wolfgang

On Apr 5, 2011, at 4:48 PM, Urs Lauterburg wrote:

> Dear Tap-lers,
> I need some advice:
> A while back I posted a reply to Cliff Bettis's ''Light Bulbs''
> thread that I was looking for a He spectral lamp with a threaded E27
> socket to replace one that broke down as part of a demonstration. In
> fact I could no longer find one with an E27 socket, but after some
> time of searching I was able to locate somebody through this
> collector's forum in Germany who
> supplied me an almost identical lamp but with a P28s socket exactly
> as shown here:
> Note that the data sheet above says under ''burning position''
> ''Vertical cap down''. Additionally I was also lucky enough to find a
> few new P28s bulb holders for this lamp in Germany as well.
> Actually this He lamp will replace one that is mounted inside a
> column along with a Na and a Ne lamp of the same type. The column is
> essentially a long metal tube with three slit shaped openings and it
> stands upright on a base. The three spectral tubes are mounted right
> behind the slits and turned on all at once. At the bottom of the
> assembly there is an incandescent bulb with just a single filament of
> the same length as the slits. We would hand out diffraction gratings
> to the students in the auditorium so they can observe and compare the
> three spectra produced by the three kinds of discharge lamps along
> with the rainbow like continuous spectrum of the incandescent
> filament.
> Now I want to make sure that I am doing this right. On the data sheet
> as shown in the first link of this post they refer to the socket as
> the ''cap''. So ''Vertical cap down'' means that the burning position
> is upright with the socket at the bottom right? just want to make
> sure with you native speakers... :-).
> I would be glad if you could confirm my interpretation as correct.
> Furthermore I noticed the the He lamp would get considerably hotter
> than the two others, Na and Ne even if the current is below the
> nominal rate. Would you think this to be normal? Does He emit more in
> the infrared than the other sources?
> Regards to all you physics demonstrators in the new world
> Urs
> Urs Lauterburg
> Physics demonstrator
> Physikalisches Institut
> University of Bern
> Switzerland