light bulb & adaptor

B

bluemonkeybird

Guest
this might sounds like a stupid question, but I have look all over for
answers, adn still pretty clueless.
Now, I like to use a #46, screw-base lamp. The rated voltage is 6.3V,
current is 250mA. I am using a DC 4.5V, 500mA adaptor. My question
is: if I use a lower Volt adaptor for this 6.3V bulb, will it wear out
sooner? Is it better for the bulb, if the Amps provided by the
adaptor is higher? I am using this particular bulb, because its life
time lasts longer, 3000 hours, unlike some lower volt bulbs, only last
for 9 hours.
Thanks for your help.

BMB
 
"bluemonkeybird" <bluemonkeybird@yahoo.com> wrote in message
news:4ff789f9.0310162011.378c2793@posting.google.com...
this might sounds like a stupid question, but I have look all over for
answers, adn still pretty clueless.
Now, I like to use a #46, screw-base lamp. The rated voltage is 6.3V,
current is 250mA. I am using a DC 4.5V, 500mA adaptor. My question
is: if I use a lower Volt adaptor for this 6.3V bulb, will it wear out
sooner? Is it better for the bulb, if the Amps provided by the
adaptor is higher? I am using this particular bulb, because its life
time lasts longer, 3000 hours, unlike some lower volt bulbs, only last
for 9 hours.
Thanks for your help.

BMB
Click to expand...
The current specification on those wall warts is not what you get, it is a
warning not to draw more than that or the thing can overheat and fail.

So, using a lower voltage wart actually gives you lower current.

To answer your question, I don't have any real facts, but I've heard it
rumored that a bulb will last longer at lower voltages.

So, I think you are ok, and probably better off (as far as bulb lifetime)
than you would be at 6.3V.

Regards,
Bob Monsen
 
"bluemonkeybird" wrote ...
this might sounds like a stupid question, but I have look
all over for answers, adn still pretty clueless.
Now, I like to use a #46, screw-base lamp. The rated
voltage is 6.3V, current is 250mA. I am using a DC 4.5V,
500mA adaptor. My question is: if I use a lower Volt
adaptor for this 6.3V bulb, will it wear out sooner?
Click to expand...
Not clear what you mean by "it", but unlikely that the lamp
OR the adapter will "wear out sooner".

Running incanescent lamps on voltages lower than their
design rating virtually always results in a longer (or MUCH
longer) lifetime. There are charts that show life expectancy
vs. operating voltage. This information is almost certainly
available online somewhere, Google is your Friend (TM).

OTOH running a lamp at lower voltage will also result in
significantly lower light output, especially for a large
(>25%) reduction such as you are proposing. There are
graphs that show this relationship to voltage also.

Is it better for the bulb, if the Amps provided by the
adaptor is higher?
Click to expand...
The adapter current rating is the maximum capacity rating.
The lamp draws whatever it is designed to draw at the given
voltage. Operating the lamp at lower voltage will cause it
to draw lower current.

I am using this particular bulb, because its life time lasts
longer, 3000 hours, unlike some lower volt bulbs, only last
for 9 hours.
Click to expand...
OK, but presumably there are other factors such as how
much light you are expecting, etc. OTOH, you would
likely get more light vs. power input (and even longer
lifetime) from a white LED, etc.
 
I've heard it rumored that a bulb will last longer at lower voltages
Bob Monsen
Click to expand...
It's more than a rumor:
http://www.google.com/search?num=100&hl=en&lr=lang_en&ie=UTF-8&oe=UTF-8&q=%22light+bulb%22+%22fire+station%22+Livermore&btnG=Google+Search
(It's more that the lamp was VERY conservatively built
relative to the known voltage source.)

The whiteness of the light suffers at lower voltage, however.
It's going to glow yellow or even orange.
 
In article <4ff789f9.0310162011.378c2793@posting.google.com>,
bluemonkeybird@yahoo.com mentioned...
this might sounds like a stupid question, but I have look all over for
answers, adn still pretty clueless.
Now, I like to use a #46, screw-base lamp. The rated voltage is 6.3V,
current is 250mA. I am using a DC 4.5V, 500mA adaptor. My question
is: if I use a lower Volt adaptor for this 6.3V bulb, will it wear out
sooner? Is it better for the bulb, if the Amps provided by the
adaptor is higher? I am using this particular bulb, because its life
time lasts longer, 3000 hours, unlike some lower volt bulbs, only last
for 9 hours.
Thanks for your help.
Click to expand...
Most wall wart adapters are unregulated, which means they put out
their rated voltage at the rated current, but with less load,
the voltage will be higher. So supposing that the one you have puts
out 6V at no load but 5V at 250 mA, then your lamp will be running at
about 1.3V less than the lamp's design voltage. Your adapter's 500 mA
rating is a maximum, so it will run at half its rating and not get
hot. So the lamp will not be at full brightness, will take less power
and last longer. If you're satisfied with the lamp's brightness, then
everything seems to be fine.

BMB
Click to expand...
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In article <vov1dbnca2im6b@corp.supernews.com>, rcrowley7@xprt.net
mentioned...
[snip]

OK, but presumably there are other factors such as how
much light you are expecting, etc. OTOH, you would
likely get more light vs. power input (and even longer
lifetime) from a white LED, etc.
Click to expand...
Not likely. Current LEDs are not a lot more efficient than light
bulbs. Read Don K's LED main page for more info.
http://members.misty.com/don/ledx.html


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
Richard Crowley wrote...
OK, but presumably there are other factors such as how
much light you are expecting, etc. OTOH, you would
likely get more light vs. power input (and even longer
lifetime) from a white LED, etc.
Click to expand...

"Watson A.Name - Watt Sun" wrote ...
Not likely. Current LEDs are not a lot more efficient than light
bulbs. Read Don K's LED main page for more info.
http://members.misty.com/don/ledx.html
Click to expand...
I didn't word that the way I was thinking, but I wasn't refering
exclusively to efficiency, but to the ability to generate a reasonable
amount of WHITE light given the two conditions:
* <6.3V, unregulated voltage
* long lifetime

"bluemonkeybird" hasn't been back to explain his fascination
with #46 screw-base lamps.
 
"Richard Crowley" <rcrowley7@xprt.net> wrote in message news:<vov1dbnca2im6b@corp.supernews.com>...
"bluemonkeybird" wrote ...
this might sounds like a stupid question, but I have look
all over for answers, adn still pretty clueless.
Now, I like to use a #46, screw-base lamp. The rated
voltage is 6.3V, current is 250mA. I am using a DC 4.5V,
500mA adaptor. My question is: if I use a lower Volt
adaptor for this 6.3V bulb, will it wear out sooner?

Not clear what you mean by "it", but unlikely that the lamp
OR the adapter will "wear out sooner".

Running incanescent lamps on voltages lower than their
design rating virtually always results in a longer (or MUCH
longer) lifetime. There are charts that show life expectancy
vs. operating voltage. This information is almost certainly
available online somewhere, Google is your Friend (TM).

OTOH running a lamp at lower voltage will also result in
significantly lower light output, especially for a large
(>25%) reduction such as you are proposing. There are
graphs that show this relationship to voltage also.

Is it better for the bulb, if the Amps provided by the
adaptor is higher?

The adapter current rating is the maximum capacity rating.
The lamp draws whatever it is designed to draw at the given
voltage. Operating the lamp at lower voltage will cause it
to draw lower current.
Click to expand...
First of all, I like to thank for all of your inputs.

I think I might buy another adaptor, maybe a little higher volt, 5 or
7 volt (I have another light bulb takes 7 volt).
The reason I was using the 4.3 volt adaptor is becuase I have two of
those laying around, and I thought it probably won'b blow the bulb up.

I am using this particular bulb, because its life time lasts
longer, 3000 hours, unlike some lower volt bulbs, only last
for 9 hours.

OK, but presumably there are other factors such as how
much light you are expecting, etc. OTOH, you would
likely get more light vs. power input (and even longer
lifetime) from a white LED, etc.
Click to expand...
A longer life time is necessary for this project.
The brightness is not so crucial. Although the current brightness is
a little too yellow.

The adapter current rating is the maximum capacity rating.
The lamp draws whatever it is designed to draw at the given
voltage. ::Operating the lamp at lower voltage will cause it
to draw lower current.::
Click to expand...
Ok, here is the point that confuses me.
I read an article a while ago, about installing an electric kiln.
"The amp rating of a kiln also determines what size circuit breaker or
fuses need to be installed for care-free firing. The circuit breaker
or fuses nee to be rated 7% higher than the amps the kiln draws when
on high.....The reason for the 7% is because the voltage provided can
vary up or down. when less voltage is delivered, the kiln pulls more
than the designated amps to make up for the loss of power"
Maybe this has nothing to do with my "bulb and adaptor" project.
But >::Operating the lamp at lower voltage will cause it
to draw lower current.::>, will not make the bulb to work harder to
draw more amps, and causing the bulb to retire earlier?

BMB
 
"bluemonkeybird" wrote ...
Ok, here is the point that confuses me.
I read an article a while ago, about installing an electric kiln.
"The amp rating of a kiln also determines what size circuit breaker or
fuses need to be installed for care-free firing. The circuit breaker
or fuses nee to be rated 7% higher than the amps the kiln draws when
on high.....The reason for the 7% is because the voltage provided can
vary up or down. when less voltage is delivered, the kiln pulls more
than the designated amps to make up for the loss of power"
Maybe this has nothing to do with my "bulb and adaptor" project.
But >::Operating the lamp at lower voltage will cause it
to draw lower current.::>, will not make the bulb to work harder to
draw more amps, and causing the bulb to retire earlier?
Click to expand...
Look up "Ohms Law". It says that there is a fixed (and predictable)
relationship between the voltage, the resistance (of the lamp in your case)
and the amount of current it will draw.

The current (in Amps) will be the voltage (in Volts) divided by the
resistance (in Ohms). Note, however, that with incandescent lamps, the
resistance changes as it gets hot (lights up). The "cold" resistance is
usually lower than the "operating" resistance.

For a given lamp and a particular voltage, the lamp will draw exactly (E/R)
amps (where E=volts and R=resistance) no more, and no less (unless the power
supply can't keep up.)

Your kiln example appears to have some sort of active loop mechanism to
attempt to keep consant power/temp even if the voltage varies. It may be an
mechanical and/or electrical or electronic device or circuit. Likely some
sort of thermostat, etc. Same effect as filling your bathtub. If there is
lower water flow, you will run it longer to get the same water level.

A simple lamp has no such feedback mechanism. Once it heats up (to whatever
power is available) it maintains the same filament resistance and won't draw
any more current than Ohm's Law predicts. If you want more light for a
given voltage, you will have to select a different lamp (ie. one with a
lower resistance that is designed for that lower voltage).
 
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