Message from discussion
Safelight bulbs??
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From: Peter <w2...@hotmail.com>
Newsgroups: rec.photo.darkroom
Subject: Re: Safelight bulbs??
Date: Mon, 4 May 2009 04:59:55 -0700 (PDT)
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On May 4, 7:24=A0am, Jean-David Beyer <jeandav...@verizon.net> wrote:
> Geoffrey S. Mendelson wrote:
> > I have a Kodak safe light that looks like a metal cone. One end screws =
into
> > a lamp socket, the other holds a round filter. It's probably from the 1=
960's
> > or older, but it's the only thing I could get here in any color except =
red.
>
> > I bought out the last of the locally availaible little red things that
> > use nightlight bulbs and a bunch of the bulbs, so I am covered for red,
> > but I wanted an orange (Wratten OC) filter as I can see much better by
> > it.
>
> > The problem I have, is that here in Israel, we have been ahead of
> > everyone else in energy saving, CFL bulbs have been sold here, and used
> > by me, since 1997. That's good, but it has caused the demand and
> > therefore the supply of low wattage incadescent bulbs to dry up.
>
> > I found a few Chinese made 7-10 watt bulbs, but they only last a few
> > hours. I found a 15 watt bulb sold for refrigerators, but it has a
> > different base and I am trying to adapt it, but may not be able to get
> > those bulbs much longer and they are very expensive being made to
> > operate at 0F and below.
>
> > The smallest incadescent bulbs that are still common here are 40 watt
> > bulbs.
>
> > What is everyone else doing for safelights?
>
> I use 7 1/2 watt 120 volt incandescent lamp bulbs. Whereas most incandesc=
ent
> lamps are designed to last about 750 hours, these little ones are designe=
d
> to last 1250 hours. I do not know if I have ever had one burn out. Now if
> you run them at 220 volts, their lifetime would be very short.
>
> My safelights came with 15 watt bulbs, and they did not seem to fog paper=
,
> but since the lights are slightly less than the 4 feet distance from my
> working surfaces, I thought it would be better to use smaller lamps in th=
em.
>
> Incandescent lamps run much longer as their input voltage is reduced. You
> might consider putting a suitable resistor in series with the bulb to dim
> the bulb slightly and increase its lifetime. The trick is to compute the
> proper resistance. If you measure the resistance of the bulb with an
> ohmmeter, it will be very low, so you will get too low a value to put in
> series. It is better to calculate it. If it is a 22 watt bulb at 220 volt=
s,
> the bulb draws 1/10 amp, so it is 2200 ohm with a hot filament. So you mi=
ght
> try a 110 to 220 ohm resistor to lower the voltage. You might wish to use=
a
> 5 watt resistor.
>
>
>
> > Thanks in advance,
>
> > Geoff.
>
> --
> =A0 =A0.~. =A0Jean-David Beyer =A0 =A0 =A0 =A0 =A0Registered Linux User 8=
5642.
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> - Show quoted text -
I think the OP needs to consider what is available locally. Those
sound good, but I am not sure what is available in Israel. If the
enclosure will withstand a higher wattage bulb, it is also possible to
reduce the illumination by simply moving the safelight farther away,
shining the light on a dark wall or covering part of the filter with
black paper. Having tried any of these suggestions it is still
necessary to test the result.
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