Graphs of current vs voltage (or power) for incadescent bulbs?

Discussion in 'Electronic Components' started by Tim Shoppa, Jun 6, 2005.

  1. Tim Shoppa

    Tim Shoppa Guest

    Does anyone know if there exists, preferably on the web, a set of
    graphs that show current vs voltage (or resistance vs RMS power or
    any other equivalent) for common low-voltage bulbs?

    I'm specifically looking for bulbs which may serve as a decent
    AC current regulator. (Think "ballast tube" if you're old enough).
    I've done some experiments with bulbs I had
    laying around and they seem pretty good in the glow-dull-red region.

    If anyone has any good rules-of-thumb (e.g. "run at 0.5 the rated
    voltage and it'll pass sqrt(0.5) the rated current") I'll gladly
    consider them
    too as starting points. Above sample rule-of-thumb was chosen out
    of think air and while it works for some bulbs it doesn't really help
    me find points which will be good for constant current operation.

    Worst case, I buy one of each kind of bulb from Mouser and make the
    tests myself :). But I'd prefer to find manufacturer's curves
    on the web. I already checked Chicago Miniature and they didn't have
    anything obvious.

    Tim.
     
    Tim Shoppa, Jun 6, 2005
    #1
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  2. Tim Shoppa

    Ian Stirling Guest

    In sci.electronics.design Tim Shoppa <> wrote:
    > Does anyone know if there exists, preferably on the web, a set of
    > graphs that show current vs voltage (or resistance vs RMS power or
    > any other equivalent) for common low-voltage bulbs?
    >
    > I'm specifically looking for bulbs which may serve as a decent
    > AC current regulator. (Think "ballast tube" if you're old enough).
    > I've done some experiments with bulbs I had
    > laying around and they seem pretty good in the glow-dull-red region.


    There are devices built for this that are much better than bulbs, comprising
    a thermistor inside a vacuum capsule.
     
    Ian Stirling, Jun 6, 2005
    #2
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  3. Tim Shoppa

    John Larkin Guest

    On 6 Jun 2005 09:30:04 -0700, "Tim Shoppa" <>
    wrote:

    >Does anyone know if there exists, preferably on the web, a set of
    >graphs that show current vs voltage (or resistance vs RMS power or
    >any other equivalent) for common low-voltage bulbs?
    >
    >I'm specifically looking for bulbs which may serve as a decent
    >AC current regulator. (Think "ballast tube" if you're old enough).
    >I've done some experiments with bulbs I had
    >laying around and they seem pretty good in the glow-dull-red region.
    >
    >If anyone has any good rules-of-thumb (e.g. "run at 0.5 the rated
    >voltage and it'll pass sqrt(0.5) the rated current") I'll gladly
    >consider them
    >too as starting points. Above sample rule-of-thumb was chosen out
    >of think air and while it works for some bulbs it doesn't really help
    >me find points which will be good for constant current operation.
    >
    >Worst case, I buy one of each kind of bulb from Mouser and make the
    >tests myself :). But I'd prefer to find manufacturer's curves
    >on the web. I already checked Chicago Miniature and they didn't have
    >anything obvious.
    >
    >Tim.



    I have a citation of

    amps = K * volts^0.541.

    which you could check against a few cases.


    John
     
    John Larkin, Jun 6, 2005
    #3
  4. Tim Shoppa

    Tim Shoppa Guest

    I wrote:
    >> [AC current regulator]


    Ian replied:
    > There are devices built for this that are much
    > better than bulbs, comprising a thermistor
    > inside a vacuum capsule.


    Real ballast tubes are iron wires inside a hydrogen-filled bulb.
    Somehow the hydrogen provides cooling that lets them deliver very
    constant current. But they are hard to come by these days.

    It seems that some small incadescent bulbs are vacuum-filled (is that
    an oxymoron?) and others are argon filled. Maybe the argon-filled ones
    will have better constant-current performance. But I don't know how to
    tell the difference just by looking.

    My requirements are not all that stiff: ten or twenty percent variation
    in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I
    thought that a properly chosen bulb (or maybe a series string or maybe
    a parallel group) may do this for me. If you can name a
    maker/distributor of these thermistor/vacuum capsule devices, and if
    they're cheap (less than a few bucks each), I am interested.

    Tim.
     
    Tim Shoppa, Jun 6, 2005
    #4
  5. Tim Shoppa

    John Larkin Guest

    On 6 Jun 2005 09:53:36 -0700, "Tim Shoppa" <>
    wrote:

    >I wrote:
    >>> [AC current regulator]

    >
    >Ian replied:
    >> There are devices built for this that are much
    >> better than bulbs, comprising a thermistor
    >> inside a vacuum capsule.

    >
    >Real ballast tubes are iron wires inside a hydrogen-filled bulb.
    >Somehow the hydrogen provides cooling that lets them deliver very
    >constant current. But they are hard to come by these days.
    >
    >It seems that some small incadescent bulbs are vacuum-filled (is that
    >an oxymoron?) and others are argon filled. Maybe the argon-filled ones
    >will have better constant-current performance. But I don't know how to
    >tell the difference just by looking.


    >
    >My requirements are not all that stiff: ten or twenty percent variation
    >in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I
    >thought that a properly chosen bulb (or maybe a series string or maybe
    >a parallel group) may do this for me. If you can name a
    >maker/distributor of these thermistor/vacuum capsule devices, and if
    >they're cheap (less than a few bucks each), I am interested.
    >


    Why not an LM317 and a resistor?

    John
     
    John Larkin, Jun 6, 2005
    #5
  6. Tim Shoppa

    Tim Shoppa Guest

    > Why not an LM317 and a resistor?

    A LM317 does not handle AC voltage all that well :).

    The need is for AC (sine wave) in, AC (sine wave) out. Converting to
    DC in the middle is possible, but I'm looking for something cheap and
    simplistic (thus light bulbs)! Some semi-sloppy current regulation is
    all I desire, and rectifying, smoothing, chopping, and filtering to get
    funked up current-regulated AC out is way too complicated.

    Tim.
     
    Tim Shoppa, Jun 6, 2005
    #6
  7. Tim Shoppa

    Phil Hobbs Guest

    John Larkin wrote:
    > On 6 Jun 2005 09:53:36 -0700, "Tim Shoppa" <>
    > wrote:
    >
    >
    >>I wrote:
    >>
    >>>>[AC current regulator]

    >>
    >>Ian replied:
    >>
    >>>There are devices built for this that are much
    >>>better than bulbs, comprising a thermistor
    >>>inside a vacuum capsule.

    >>
    >>Real ballast tubes are iron wires inside a hydrogen-filled bulb.
    >>Somehow the hydrogen provides cooling that lets them deliver very
    >>constant current. But they are hard to come by these days.
    >>
    >>It seems that some small incadescent bulbs are vacuum-filled (is that
    >>an oxymoron?) and others are argon filled. Maybe the argon-filled ones
    >>will have better constant-current performance. But I don't know how to
    >>tell the difference just by looking.

    >
    >
    >>My requirements are not all that stiff: ten or twenty percent variation
    >>in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I
    >>thought that a properly chosen bulb (or maybe a series string or maybe
    >>a parallel group) may do this for me. If you can name a
    >>maker/distributor of these thermistor/vacuum capsule devices, and if
    >>they're cheap (less than a few bucks each), I am interested.
    >>

    >
    >
    > Why not an LM317 and a resistor?
    >
    > John
    >
    >


    Across a bridge rectifier.

    Cheers,

    Phil Hobbs
     
    Phil Hobbs, Jun 6, 2005
    #7
  8. Tim Shoppa

    Jim Thompson Guest

    On 6 Jun 2005 11:51:31 -0700, "Tim Shoppa" <>
    wrote:

    >> Why not an LM317 and a resistor?

    >
    >A LM317 does not handle AC voltage all that well :).
    >
    >The need is for AC (sine wave) in, AC (sine wave) out. Converting to
    >DC in the middle is possible, but I'm looking for something cheap and
    >simplistic (thus light bulbs)! Some semi-sloppy current regulation is
    >all I desire, and rectifying, smoothing, chopping, and filtering to get
    >funked up current-regulated AC out is way too complicated.
    >
    >Tim.


    I've used CdS photo cells (resistive) controlled by an incandescent
    bulb tweaked by a comparator.

    ...Jim Thompson
    --
    | James E.Thompson, P.E. | mens |
    | Analog Innovations, Inc. | et |
    | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
    | Phoenix, Arizona Voice:(480)460-2350 | |
    | E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
    | http://www.analog-innovations.com | 1962 |

    I love to cook with wine. Sometimes I even put it in the food.
     
    Jim Thompson, Jun 6, 2005
    #8
  9. Tim Shoppa

    John Fields Guest

    On Mon, 06 Jun 2005 11:36:51 -0700, John Larkin
    <> wrote:

    >On 6 Jun 2005 09:53:36 -0700, "Tim Shoppa" <>
    >wrote:
    >
    >>I wrote:
    >>>> [AC current regulator] <-----------------------------------------------+

    >> |
    >>Ian replied: |
    >>> There are devices built for this that are much |
    >>> better than bulbs, comprising a thermistor |
    >>> inside a vacuum capsule. |

    >> |
    >>Real ballast tubes are iron wires inside a hydrogen-filled bulb. |
    >>Somehow the hydrogen provides cooling that lets them deliver very |
    >>constant current. But they are hard to come by these days. |
    >> |
    >>It seems that some small incadescent bulbs are vacuum-filled (is that |
    >>an oxymoron?) and others are argon filled. Maybe the argon-filled ones |
    >>will have better constant-current performance. But I don't know how to |
    >>tell the difference just by looking. |

    > |
    >> |
    >>My requirements are not all that stiff: ten or twenty percent variation |
    >>in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I |
    >>thought that a properly chosen bulb (or maybe a series string or maybe |
    >>a parallel group) may do this for me. If you can name a |
    >>maker/distributor of these thermistor/vacuum capsule devices, and if |
    >>they're cheap (less than a few bucks each), I am interested. |
    >> |

    > |
    >Why not an LM317 and a resistor? ------------------------------------------+


    ---
    ;)


    --
    John Fields
    Professional Circuit Designer
     
    John Fields, Jun 6, 2005
    #9
  10. Tim Shoppa

    John Larkin Guest

    On Mon, 06 Jun 2005 14:54:03 -0400, Phil Hobbs
    <> wrote:

    >John Larkin wrote:
    >> On 6 Jun 2005 09:53:36 -0700, "Tim Shoppa" <>
    >> wrote:
    >>
    >>
    >>>I wrote:
    >>>
    >>>>>[AC current regulator]
    >>>
    >>>Ian replied:
    >>>
    >>>>There are devices built for this that are much
    >>>>better than bulbs, comprising a thermistor
    >>>>inside a vacuum capsule.
    >>>
    >>>Real ballast tubes are iron wires inside a hydrogen-filled bulb.
    >>>Somehow the hydrogen provides cooling that lets them deliver very
    >>>constant current. But they are hard to come by these days.
    >>>
    >>>It seems that some small incadescent bulbs are vacuum-filled (is that
    >>>an oxymoron?) and others are argon filled. Maybe the argon-filled ones
    >>>will have better constant-current performance. But I don't know how to
    >>>tell the difference just by looking.

    >>
    >>
    >>>My requirements are not all that stiff: ten or twenty percent variation
    >>>in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I
    >>>thought that a properly chosen bulb (or maybe a series string or maybe
    >>>a parallel group) may do this for me. If you can name a
    >>>maker/distributor of these thermistor/vacuum capsule devices, and if
    >>>they're cheap (less than a few bucks each), I am interested.
    >>>

    >>
    >>
    >> Why not an LM317 and a resistor?
    >>
    >> John
    >>
    >>

    >
    >Across a bridge rectifier.
    >


    Or back-to-back, with schottkies?

    PTC thermistor?


    John
     
    John Larkin, Jun 6, 2005
    #10
  11. In article <>, John Larkin wrote:
    >On 6 Jun 2005 09:53:36 -0700, "Tim Shoppa" <>
    >wrote:
    >
    >>I wrote:
    >>>> [AC current regulator]

    >>
    >>Ian replied:
    >>> There are devices built for this that are much
    >>> better than bulbs, comprising a thermistor
    >>> inside a vacuum capsule.

    >>
    >>Real ballast tubes are iron wires inside a hydrogen-filled bulb.
    >>Somehow the hydrogen provides cooling that lets them deliver very
    >>constant current. But they are hard to come by these days.
    >>
    >>It seems that some small incadescent bulbs are vacuum-filled (is that
    >>an oxymoron?) and others are argon filled. Maybe the argon-filled ones
    >>will have better constant-current performance. But I don't know how to
    >>tell the difference just by looking.

    >
    >>
    >>My requirements are not all that stiff: ten or twenty percent variation
    >>in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I
    >>thought that a properly chosen bulb (or maybe a series string or maybe
    >>a parallel group) may do this for me. If you can name a
    >>maker/distributor of these thermistor/vacuum capsule devices, and if
    >>they're cheap (less than a few bucks each), I am interested.

    >
    >Why not an LM317 and a resistor?


    The LM317 does make a nice current regulator.

    But should Tim Shoppa have some requirement or desire to use a lamp
    (wants the regulator to glow?) then I would parallel a bunch of 25 watt
    A19 "standard" or "soft white" incandescents. (I doubt these particular
    ones glow much below 18 volts because of greater filament cooling by the
    gas, although higher and lower wattages and tubular "refrigerator"
    /"showcase" lamps up to 40 watts [vacuum] do.)

    Incandescents usually have a vacuum if very low wattage and/or low
    current - less than roughly 25 watts per inch of visibly apparent
    length-plus-diameter of filament. Incandescents of higher power/current
    than this tend to be gas filled. Lower current incandescents have a
    vacuum instead of a gas because the heat conduction losses by the gas
    outweigh the benefits of gas slowing down filament evaporation and
    permitting a higher filament temperature. This is because a narrower
    filament has a higher temperature gradient in the gas around the filament,
    which largely cancels out the lower filament surface area.
    Incandescents of design that barely has a net benefit by the gas have
    greatest effect of the gas - current varying less with voltage, and light
    output and life varying more with voltage than is the case with other
    incandescents. And these differences in performance variation with
    voltage are greater at low voltage - especially near or a little below the
    threshold of visibly producing light - than they are near design voltage.

    I once many years ago plotted current as a function of voltage for a
    gas filled flashlight lamp (HPR52), and found the curve to be almost
    flat in some range of low voltages - I believe about .3-.8 volt.

    - Don Klipstein ()
     
    Don Klipstein, Jun 6, 2005
    #11
  12. Tim Shoppa

    Fred Bartoli Guest

    "Tim Shoppa" <> a écrit dans le message de
    news:...
    > > Why not an LM317 and a resistor?

    >
    > A LM317 does not handle AC voltage all that well :).
    >
    > The need is for AC (sine wave) in, AC (sine wave) out. Converting to
    > DC in the middle is possible, but I'm looking for something cheap and
    > simplistic (thus light bulbs)! Some semi-sloppy current regulation is
    > all I desire, and rectifying, smoothing, chopping, and filtering to get
    > funked up current-regulated AC out is way too complicated.
    >


    So put the 317 inside a rectifier bridge (if the discontinuity isn't too
    sloppy).


    --
    Thanks,
    Fred.
     
    Fred Bartoli, Jun 6, 2005
    #12
  13. Tim Shoppa

    Tim Shoppa Guest

    > I've used CdS photo cells (resistive) controlled
    > by an incandescent bulb tweaked by a comparator.


    And I've used this idea with great success in Wein bridge oscillators.

    But in my latest need, the power dissipation is 300mA x 14V or around 4
    or 5 watts. A CdS photocell isn't good for anywhere near that much
    power.

    Tim.
     
    Tim Shoppa, Jun 6, 2005
    #13
  14. Tim Shoppa

    Guest

    In sci.electronics.design Tim Shoppa <> wrote:
    >Does anyone know if there exists, preferably on the web, a set of
    >graphs that show current vs voltage (or resistance vs RMS power or
    >any other equivalent) for common low-voltage bulbs? I'm specifically
    >looking for bulbs which may serve as a decent AC current regulator.


    I have a Wagner Lighting automotive lamp catalog that has a table with
    some of this information, but it's general data, not specific to each
    lamp number.

    I once heard that there are empirical formulas for this involving odd
    things like thirteenth and ninth powers, but I don't recall exactly
    what they are.

    I have taken the liberty of cross-posting (and setting followups)
    to sci.engr.lighting, which should yield much better info.

    Matt Roberds
     
    , Jun 6, 2005
    #14
  15. On 6 Jun 2005 09:53:36 -0700, the renowned "Tim Shoppa"
    <> wrote:

    >I wrote:
    >>> [AC current regulator]

    >
    >Ian replied:
    >> There are devices built for this that are much
    >> better than bulbs, comprising a thermistor
    >> inside a vacuum capsule.

    >
    >Real ballast tubes are iron wires inside a hydrogen-filled bulb.
    >Somehow the hydrogen provides cooling that lets them deliver very
    >constant current. But they are hard to come by these days.


    Eg. the old Amperite devices. Last I saw them they were going for
    upwards of $100 a pop.

    >It seems that some small incadescent bulbs are vacuum-filled (is that
    >an oxymoron?) and others are argon filled. Maybe the argon-filled ones
    >will have better constant-current performance. But I don't know how to
    >tell the difference just by looking.
    >
    >My requirements are not all that stiff: ten or twenty percent variation
    >in (nominal) 300mA current over, say, 6 to 18V drop would be fine. I
    >thought that a properly chosen bulb (or maybe a series string or maybe
    >a parallel group) may do this for me. If you can name a
    >maker/distributor of these thermistor/vacuum capsule devices, and if
    >they're cheap (less than a few bucks each), I am interested.
    >
    >Tim.


    Here's an old graph of current vs. voltage for line voltage Xmas tree
    type bulbs:

    http://www.speff.com/bulb.gif


    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
     
    Spehro Pefhany, Jun 6, 2005
    #15
  16. Tim Shoppa

    Guy Macon Guest

    Tim Shoppa wrote:

    >Does anyone know if there exists, preferably on the web, a set of
    >graphs that show current vs voltage (or resistance vs RMS power or
    >any other equivalent) for common low-voltage bulbs? I'm specifically
    >looking for bulbs which may serve as a decent AC current regulator.


    Any such set of curves would also have to account for time.
    At a constant voltage, the resistance/current changes as the
    bulb warms up.
     
    Guy Macon, Jun 6, 2005
    #16
  17. In article <7y1pe.42735$Wr.42557@fed1read04>, wrote:
    >In sci.electronics.design Tim Shoppa <> wrote:
    >>Does anyone know if there exists, preferably on the web, a set of
    >>graphs that show current vs voltage (or resistance vs RMS power or
    >>any other equivalent) for common low-voltage bulbs? I'm specifically
    >>looking for bulbs which may serve as a decent AC current regulator.

    >
    >I have a Wagner Lighting automotive lamp catalog that has a table with
    >some of this information, but it's general data, not specific to each
    >lamp number.
    >
    >I once heard that there are empirical formulas for this involving odd
    >things like thirteenth and ninth powers, but I don't recall exactly
    >what they are.
    >
    >I have taken the liberty of cross-posting (and setting followups)
    >to sci.engr.lighting, which should yield much better info.


    I somewhat remember the "one-size-fits-all rule" at least sometimes
    saying that current is proportional to voltage raised to the .42 power.

    I have found this exponent to be more like .52 with a high current gas
    filled lamp (9005 halogen high beam bulb), and .57 with a vacuum lamp
    (either 25 or 40 watt 120V "T10" showcase/refrigerator lamp). I expect
    this exponent to be less with gas filled lamps with design current a
    lot less than that of the 9005.
    I also expect this exponent to vary with voltage when the voltage gets
    low - often decreases in gas filled lamps, but has to increase towards 1
    once the voltage decreases so much that the filament temperature is close
    to room temperature.

    - Don Klipstein ()
     
    Don Klipstein, Jun 6, 2005
    #17
  18. Tim Shoppa

    John Perry Guest

    Fred Bartoli wrote:
    > "Tim Shoppa" <> a écrit dans le message de
    > news:...
    >
    >>>Why not an LM317 and a resistor?

    >>
    >>A LM317 does not handle AC voltage all that well :).
    >>
    >>The need is for AC (sine wave) in, AC (sine wave) out. Converting to
    >>DC in the middle is possible, but I'm looking for something cheap and
    >>simplistic (thus light bulbs)! Some semi-sloppy current regulation is
    >>all I desire, and rectifying, smoothing, chopping, and filtering to get
    >>funked up current-regulated AC out is way too complicated.
    >>

    >
    >
    > So put the 317 inside a rectifier bridge (if the discontinuity isn't too
    > sloppy).
    >
    >

    ....And if it is too high, could you use it in series with a 14V power
    transformer?

    John Perry
     
    John Perry, Jun 6, 2005
    #18
  19. Tim Shoppa

    truegridtz Guest

    "Tim Shoppa" <> wrote in message
    news:...
    > Does anyone know if there exists, preferably on the web, a set of
    > graphs that show current vs voltage (or resistance vs RMS power or
    > any other equivalent) for common low-voltage bulbs?
    >
    > I'm specifically looking for bulbs which may serve as a decent
    > AC current regulator. (Think "ballast tube" if you're old enough).
    > I've done some experiments with bulbs I had
    > laying around and they seem pretty good in the glow-dull-red region.
    >
    > If anyone has any good rules-of-thumb (e.g. "run at 0.5 the rated
    > voltage and it'll pass sqrt(0.5) the rated current") I'll gladly
    > consider them
    > too as starting points. Above sample rule-of-thumb was chosen out
    > of think air and while it works for some bulbs it doesn't really help
    > me find points which will be good for constant current operation.
    >
    > Worst case, I buy one of each kind of bulb from Mouser and make the
    > tests myself :). But I'd prefer to find manufacturer's curves
    > on the web. I already checked Chicago Miniature and they didn't have
    > anything obvious.
    >
    > Tim.


    I am not to sure exactly what they do, B&K tube testers use a pair of bulbs
    to regulate something. I recall that they are number 55. B&K says they
    must be replaced as a pair from the same manufacturer.

    They have something to do with the meter. If one of them burns out the
    meter goes crazy. Thought this might give you a clue. Good Luck, Mark
    >
     
    truegridtz, Jun 6, 2005
    #19
  20. Tim Shoppa

    Luhan Monat Guest

    Tim Shoppa wrote:
    >>Why not an LM317 and a resistor?

    >
    >
    > A LM317 does not handle AC voltage all that well :).
    >
    > The need is for AC (sine wave) in, AC (sine wave) out. Converting to
    > DC in the middle is possible, but I'm looking for something cheap and
    > simplistic (thus light bulbs)! Some semi-sloppy current regulation is
    > all I desire, and rectifying, smoothing, chopping, and filtering to get
    > funked up current-regulated AC out is way too complicated.
    >
    > Tim.
    >


    Hewlett Packard used a #49 lamp for there variable sine wave generator.
    To get an idea for a specific bulb: measure the 'cold' resistance with
    an ohmmeter; calculate the 'hot' resistance by dividing the power by the
    current squared. Most lamp have about a 10:1 ratio.

    I find them very useful in design of protection circuits.

    --
    Luhan Monat: luhanis(at)yahoo(dot)com
    http://members.cox.net/berniekm
    "Any sufficiently advanced magick is
    indistinguishable from technology."
     
    Luhan Monat, Jun 7, 2005
    #20
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