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What bulb for dynamo.

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UK and Europe
Published
12 July 2005
Last activity
22 July 2005
Original author
Martin Dann
Posts
334
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  1. "Steven" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    Clive, that's complete and utter bollocks.

    If your contention were correct, no one would have cycled at night,
    because most
    roads were unlit, and according to your hypothosis everyone would have got
    knocked down every time thy had to stop at a T junction to await a car
    turning
    into the road they were turning out of.

    Nope. You forget there's somebody else involved here. I reckon most drivers
    do actually look where they're going, and consequently most drivers wouldn't
    have hit the girl in question. Hence my original post : she would have been
    hit anyway.

    (here most = nearly all)

    clive

  2. "Just zis Guy, you know?" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    Quoted message said:

    I don't know. Personaly I carry spare batteries.

    Bingo. And the equivalent for a bike with dynamo lighting is?... :-D

    I notice he doesn't carry spare bulbs. Battery lights aren't immune to bulb
    failure either...

    cheers,
    clive

  3. On Wed, 13 Jul 2005 19:41:55 +0100, "Clive George" <[email hidden]>

    Quoted message said:

    "Just zis Guy, you know?" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    Quoted message said:

    I don't know. Personaly I carry spare batteries.

    Bingo. And the equivalent for a bike with dynamo lighting is?... :-D

    I notice he doesn't carry spare bulbs. Battery lights aren't immune to bulb
    failure either...

    I wear socks.

    From this, can you, by the same logic you use above, deduce that I don't wear
    trousers?

  4. "Steven" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    On Wed, 13 Jul 2005 19:41:55 +0100, "Clive George"
    <[email hidden]>

    Quoted message said:

    "Just zis Guy, you know?" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    >I don't know. Personaly I carry spare batteries.

    Bingo. And the equivalent for a bike with dynamo lighting is?... :-D

    I notice he doesn't carry spare bulbs. Battery lights aren't immune to
    bulb
    failure either...

    I wear socks.

    From this, can you, by the same logic you use above, deduce that I don't
    wear
    trousers?

    Do you carry spare bulbs for your battery lamps then? If so, why didn't you
    mention it earlier? It would seem pertinent, since we were talking about
    bulb failure.

    clive

  5. On Wed, 13 Jul 2005 20:07:05 +0100, "Clive George" <[email hidden]>

    Quoted message said:

    Do you carry spare bulbs for your battery lamps then? If so, why didn't you
    mention it earlier? It would seem pertinent, since we were talking about
    bulb failure.

    It wasn't pertinant to the particular part of the thread where it was mentioned,
    because at that point Guy was questioning why battery lights could be considered
    safe, since the batteries would go flat.

    The issue of the spare batteries was relevant, but the issue of spare bulbs
    wasn't because this is admitted common failure mode for both systems. (Although
    there's no possibility of the rear battery light failing because the front does,
    or vice versa).

  6. "Steven" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    On Wed, 13 Jul 2005 20:07:05 +0100, "Clive George"
    <[email hidden]>

    Quoted message said:

    Do you carry spare bulbs for your battery lamps then? If so, why didn't
    you
    mention it earlier? It would seem pertinent, since we were talking about
    bulb failure.

    It wasn't pertinant to the particular part of the thread where it was
    mentioned,
    because at that point Guy was questioning why battery lights could be
    considered
    safe, since the batteries would go flat.

    The issue of the spare batteries was relevant, but the issue of spare
    bulbs
    wasn't because this is admitted common failure mode for both systems.
    (Although
    there's no possibility of the rear battery light failing because the front
    does,
    or vice versa).

    Translation : No.

    Next question : Why not?

    clive

  7. In message <[email hidden]>

    Peter Clinch said:
    Martin Dann said:

    I have an old cateye dual daylight system (push fit flange bulbs), the
    battery has died again, and I am fed up with haveing to charge lights every
    few days. I often forget. So am strongly thinking of getting a dynamo system.

    The Shimano NX32 6V 3W Dynohub with Mavic Rim look nice.

    The newer Shimano Ultegra and XT dynohubs aren't much more and are
    reckoned to be quite an improvement over the Nexus. See
    http://kinetics.org.uk/html/shimano_hubs.shtml

    Is it possible to get these in wheels pre-built, I am not sure I fancy
    building one myself. (Or paying a lot of money for someeone to build one).

    Wiggle sell whole wheels with auto switch, for 85 pounds sterling and 46
    shinny pennies (once a ten perecent discount is applied, and sufficent
    other stuff has been ordered). Several other on-line places sell these
    at 95-ish ukp.

    The SON hubs look far too expensive for me.

    Quoted message said:
    Quoted message said:


    What bulb(s) do I need. Do I need special dynamo bulbs, or will any
    6V3W push fit bulb do.

    Can I use cateye 2.4 W bulbs?

    If you're not running a tail-light it won't be a huge amount of time
    before you blow it. It'll work as an emergency spare, maybe for a few
    months, but it'll blow well within the life of a 3W bulb.

    I got Roos an Ultegra hub built into a wheel and a B&M Lumotec Oval
    Senso Plus (with a 3W bulb) for Christmas, and it's done very well. The
    lamp has a light sensor and just turns itself on as light falls. Sounds
    gimmicky but works very well, and eliminating the mechanical switch
    makes it potentially more reliable.

    Zog The Undeniable said:

    Er, no, you can use 2.4W with or without tail lamp, but of you have no
    tail lamp then why not use 3W. Which is prolly what you meant?

    I meant 2.4W as I have these to hand. Looks like a phillips 3W to be bought.

    On a different note, kinetics sell them facy stick on glass lens mirrors
    that were in a diferent thread a while back.

    http://kinetics.org.uk/html/mirrors.shtml

    --
    According to the human genome project, humans are 50-60% bananas.
    When emailing me, please include the word Banana in the subject line.

  8. On Wed, 13 Jul 2005 21:25:03 +0100, "Clive George" <[email hidden]>

    Quoted message said:

    "Steven" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    On Wed, 13 Jul 2005 20:07:05 +0100, "Clive George"
    <[email hidden]>

    Quoted message said:

    Do you carry spare bulbs for your battery lamps then? If so, why didn't
    you
    mention it earlier? It would seem pertinent, since we were talking about
    bulb failure.

    It wasn't pertinant to the particular part of the thread where it was
    mentioned,
    because at that point Guy was questioning why battery lights could be
    considered
    safe, since the batteries would go flat.

    The issue of the spare batteries was relevant, but the issue of spare
    bulbs
    wasn't because this is admitted common failure mode for both systems.
    (Although
    there's no possibility of the rear battery light failing because the front
    does,
    or vice versa).

    Translation : No.

    It needs no translation, it's utterly irrelevant to the topic under discussion.

    End of story.

  9. "m-gineering" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    ian henden said:


    "m-gineering" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    Martin Dann wrote:
    >
    > I have an old cateye dual daylight system (push fit flange bulbs), the
    > battery has died again, and I am fed up with haveing to charge lights
    > every
    > few days. I often forget. So am strongly thinking of getting a dynamo
    > system.
    >
    > The Shimano NX32 6V 3W Dynohub with Mavic Rim look nice.
    >
    > What bulb(s) do I need. Do I need special dynamo bulbs, or will any
    > 6V3W push fit bulb do.
    >
    This still won't protect the bulb from overvoltage on descents, as a
    batterylight won't have the necessary zehner to limit overvoltage.

    A decent dynamo will have an inductive reactance such that, as the
    generated
    emf increases with speed, so the frequency of the generated voltage will
    also increase, and the voltage drop due to 2*pi*f*L will also increase,
    this
    being subtracted (in the vertical direction) from the generated voltage
    (which will form the hypotenuse of a rt angle triangle) leaving the
    resistive (horizontal) component (i e the lamp voltage) *almost*
    constant.
    True, it won't be *exactly* constant.

    This, of course, is why dynamo lamps still work at quite low speed. But
    not
    when stationary - you ought to switch over to battery backup when
    stopped.

    but bulblife L= (U/Un)^-k (k=10-11) ie at 7.2 v (upper voltage according
    to DIN) life is only 13%.

    --
    ---
    Marten Gerritsen

    INFOapestaartjeM-GINEERINGpuntNL
    www.m-gineering.nl

    Then it follows that you should keep your speed down at night, to such a
    speed that your light will not fail and leave you hurtling along in pitch
    black!!!

    :0)

    (seriously .... if someone IS contemplating really fast travel at night,
    then surely they ought to have TWO working front lights, so that when one
    fails, they can still see where they are going?)

    --
    IanH

  10. "Chris Slade" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    ian henden said:

    "Buck" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:


    The word "bulb" refers to the shape, seeds grow, bulbs are just bulb
    shaped.


    Not to an electrical engineer.

    Bulbs grow, Lamps glow.

    From the Wordsworth dictionary of science & technology:

    Bulb (Elec.Eng.) The gas-tight envelope, usually glass, which encloses the
    electrodes of a thermionic valve or of an electric discharge lamp, or the
    filament of an electric filament lamp.

    Any further comments?

    I trust my erstwhile Science teacher.

    --
    ianH

  11. "Just zis Guy, you know?" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    Simon Brooke said:

    When seeking to correct other people, first check that you are
    right. Otherwise you may appear to be an ignorant [censored].

    Are you suggesting that Henden might only *appear* to be an ignorant
    [censored]? ;-)

    Guy
    --


    Whereas we all know that Guy actually *is* one.
    Now FOAD.

    ianH

  12. "m-gineering" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    Steven said:


    Andreas Oehler said:

    Both are not
    designed to run a 6V-2.4W bulb on a 6V-3W dynamo for extended time.

    This is incorrect.

    A wattage rating for a dynamo is an indication of its maximum output
    (0.5amps at
    6volts).

    You *cannot* damage a 6v 2.4w lamp by running on a generator with an
    output of
    6v. The resistance of the lamp (15 ohms) will limit the current to 0.4
    amps.

    Even if the dynamo was rated at 100w, you could quite safely run a 1w
    lamp on
    it.

    Not so, bicycle dynamo's are constant current devices and churn out 0.5
    amps. This is the reason the rearlight glows very bright (very briefly)
    when the front bulb blows, and also explains why it is possible to drive
    an ordinary desklamp and a radio from a SON if you turn it fast enough.
    More sane use is to use the dynamo to drive two headlights in series

    That is not sane ... when one stops, so does the other, then you can't see
    where you are going!!!

    try "parallel"

    --
    IanH

  13. ian henden said:


    "m-gineering" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    Steven said:


    On Tue, 12 Jul 2005 22:34:59 +0200, Andreas Oehler
    <[email hidden]> wrote:

    > Both are not
    >designed to run a 6V-2.4W bulb on a 6V-3W dynamo for extended time.

    This is incorrect.

    A wattage rating for a dynamo is an indication of its maximum output
    (0.5amps at
    6volts).

    You *cannot* damage a 6v 2.4w lamp by running on a generator with an
    output of
    6v. The resistance of the lamp (15 ohms) will limit the current to 0.4
    amps.

    Even if the dynamo was rated at 100w, you could quite safely run a 1w
    lamp on
    it.

    Not so, bicycle dynamo's are constant current devices and churn out 0.5
    amps. This is the reason the rearlight glows very bright (very briefly)
    when the front bulb blows, and also explains why it is possible to drive
    an ordinary desklamp and a radio from a SON if you turn it fast enough.
    More sane use is to use the dynamo to drive two headlights in series

    That is not sane ... when one stops, so does the other, then you can't see
    where you are going!!!

    try "parallel"

    try a basic grasp of the subject before posting

    --
    ---
    Marten Gerritsen

    INFOapestaartjeM-GINEERINGpuntNL
    www.m-gineering.nl

  14. m-gineering said:

    Not so, bicycle dynamo's are constant current devices and churn out
    0.5 amps. This is the reason the rearlight glows very bright (very
    briefly) when the front bulb blows, and also explains why it is
    possible to drive an ordinary desklamp and a radio from a SON if you
    turn it fast enough. More sane use is to use the dynamo to drive two
    headlights in series

    However, with a Lightspin They advise that two headlights can be used, but
    in parallel.

    --
    Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
    Whatever it is, I'd like it in mango & passion fruit, please.

  15. On Wed, 13 Jul 2005 22:56:23 +0100, "Just zis Guy, you know?" <[email hidden]>
    wrote:

    A load of old toss.

    I can't even be bothered to read all this [censored], Guy.

    You're so far off the rails it's impossible to discuss the matter logically.

    I told you I've no axe to gring concerning modern dynamo systems. They may be
    safe, I really don't know. At the moment, I really don't care. And yet you're
    still banging on about it.

    As to the incident with the little girl on the bike, you are so desperate to
    deny the part played by the inadequate dynamo lighting system that you are
    blinding yourself to all logic and reason.

    You seem quite incapable of grasping the fact that is obvious to just about any
    rational person, that there are many contributing factors to an accident.

    One of the main contributing factors to the accident mentioned was the fact that
    the dynamo system involved was *completly useless* when the cycle was not in
    motion.

    Go ahead and bang on and on about how it was soley the driver's fault. You just
    look more and more like a sad, self deluding fanatic.

  16. On Thu, 14 Jul 2005 07:26:04 GMT, "ian henden" <[email hidden]>

    Quoted message said:

    I trust my erstwhile Science teacher.

    Unwise. My erstwhile science teacher told me that magnetism was not
    the result of the electrons in a bit of material going round the
    nuclei in the same direction. Turns out it is and he was wrong.

    Do you ever discuss weight in kilogrammes?

    Guy
    --
    May contain traces of irony. Contents liable to settle after posting.
    http://www.chapmancentral.co.uk

    88% of helmet statistics are made up, 65% of them at CHS, Puget Sound

  17. Dave Larrington said:


    m-gineering said:

    Not so, bicycle dynamo's are constant current devices and churn out
    0.5 amps. This is the reason the rearlight glows very bright (very
    briefly) when the front bulb blows, and also explains why it is
    possible to drive an ordinary desklamp and a radio from a SON if you
    turn it fast enough. More sane use is to use the dynamo to drive two
    headlights in series

    However, with a Lightspin They advise that two headlights can be used, but
    in parallel.

    Correct, the lightspin is the odd one out. To avoid slippage higher
    force against the tyre might be needed, which will decrease efficiency
    somewhat. AFAIK topspeed is max 60 kmh (38 mph)

    --
    ---
    Marten Gerritsen

    INFOapestaartjeM-GINEERINGpuntNL
    www.m-gineering.nl

  18. On Thu, 14 Jul 2005 10:36:28 GMT, [email hidden] (Steven)

    Quoted message said:

    A load of old toss.
    I can't even be bothered to read all this [censored], Guy.

    Ah, the sign of reasoned argument everywhere.

    Quoted message said:

    You're so far off the rails it's impossible to discuss the matter logically.

    So you say. If by logically you mean by reference to swearwords and
    SHOUTING then I've no doubt you're right.

    Quoted message said:

    I told you I've no axe to gring concerning modern dynamo systems. They may be
    safe, I really don't know. At the moment, I really don't care. And yet you're
    still banging on about it.

    Clearly you are absolutely determined not to see that there are two
    strands to this argument.

    Quoted message said:

    As to the incident with the little girl on the bike, you are so desperate to
    deny the part played by the inadequate dynamo lighting system that you are
    blinding yourself to all logic and reason.

    As I said, you are accusing the girl (or rather, her parents) of
    making a negligent choice. With reference to the state of the art and
    the state of knowledge at the time, I dispute that.

    Perhaps, instead of resorting to proof by assertion, you can cite some
    actual data which shows that the system you denounce as lethally
    dangerous was actually responsible for any meaningful number of
    deaths? That users of this system were more likely to die than users
    of other systems?

    Or was it the case that a conscious choice was made which balanced
    risks at some points of a journey with other risks at other points of
    the journey?

    Quoted message said:

    You seem quite incapable of grasping the fact that is obvious to just about any
    rational person, that there are many contributing factors to an accident.

    Oh, I have no problem with that. I have a problem with your statement
    "a policeman came to give us a talk on bike safety, and told us never
    to use dynamo lamps as they were dangerous. He related the story of a
    girl who'd been killed because she was using dynamo lights."

    Where are the other contributing factors in that statement? You said
    she had been killed "because she was using dynamo lights". Actually
    the cause was a negligent driver.

    You'd get the same argument if you said a girl was raped "because she
    was wearing a short skirt".

    But since you "can't even be bothered" to read what I wrote I guess
    you'll not recognise that.

    Quoted message said:

    One of the main contributing factors to the accident mentioned was the fact that
    the dynamo system involved was *completly useless* when the cycle was not in
    motion.

    So you say. But there is no indication that the battery systems of
    the time would have made any difference, given that the incident as
    described shows the driver coming from the side.

    Quoted message said:

    Go ahead and bang on and on about how it was soley the driver's fault. You just
    look more and more like a sad, self deluding fanatic.

    So you say. And in truth I am a fanatic. I am fanatically opposed to
    blaming cyclists when negligent drivers kill them, especially on the
    grounds of safety choices they have made based on the best information
    available at the time.

    That something "sounds very dangerous" does not mean it is, and even
    if it were to increase the risk, that will *never* excuse a driver who
    is simply not looking where he is going. It's right up there with
    "aggressive" street furniture and "dangerous" trees in the litany of
    cager evasions.

    Guy
    --
    May contain traces of irony. Contents liable to settle after posting.
    http://www.chapmancentral.co.uk

    88% of helmet statistics are made up, 65% of them at CHS, Puget Sound

  19. Just zis Guy said:

    On Wed, 13 Jul 2005 14:51:04 GMT, [email hidden] (Steven)

    Quoted message said:
    Quoted message said:

    >They sound very dangerous to me. Someone inherits a bike with a dynamo.


    [...]

    Quoted message said:

    And as I say, my advice has always been to have multiple lights. A
    battery rear light can fail just as easily and just as un-noticed.

    In the case of "Someone inherits a bike with" D-cell Ever Ready lights,
    a damn sight more easily....

  20. Just zis Guy, you know? wrote in
    news:[email hidden]:

    Quoted message said:

    On Thu, 14 Jul 2005 10:36:28 GMT, [email hidden] (Steven)

    Quoted message said:

    A load of old toss.
    I can't even be bothered to read all this [censored], Guy.

    Ah, the sign of reasoned argument everywhere.

    Quoted message said:

    You're so far off the rails it's impossible to discuss the matter
    logically.

    So you say. If by logically you mean by reference to swearwords and
    SHOUTING then I've no doubt you're right.

    Quoted message said:

    I told you I've no axe to gring concerning modern dynamo systems. They
    may be safe, I really don't know. At the moment, I really don't care.
    And yet you're still banging on about it.

    Clearly you are absolutely determined not to see that there are two
    strands to this argument.

    Quoted message said:

    As to the incident with the little girl on the bike, you are so
    desperate to deny the part played by the inadequate dynamo lighting
    system that you are blinding yourself to all logic and reason.

    As I said, you are accusing the girl (or rather, her parents) of
    making a negligent choice. With reference to the state of the art and
    the state of knowledge at the time, I dispute that.

    Perhaps, instead of resorting to proof by assertion, you can cite some
    actual data which shows that the system you denounce as lethally
    dangerous was actually responsible for any meaningful number of
    deaths? That users of this system were more likely to die than users
    of other systems?

    Or was it the case that a conscious choice was made which balanced
    risks at some points of a journey with other risks at other points of
    the journey?

    Quoted message said:

    You seem quite incapable of grasping the fact that is obvious to just
    about any rational person, that there are many contributing factors to
    an accident.

    Oh, I have no problem with that. I have a problem with your statement
    "a policeman came to give us a talk on bike safety, and told us never
    to use dynamo lamps as they were dangerous. He related the story of a
    girl who'd been killed because she was using dynamo lights."

    Where are the other contributing factors in that statement? You said
    she had been killed "because she was using dynamo lights". Actually
    the cause was a negligent driver.

    You'd get the same argument if you said a girl was raped "because she
    was wearing a short skirt".

    But since you "can't even be bothered" to read what I wrote I guess
    you'll not recognise that.

    Quoted message said:

    One of the main contributing factors to the accident mentioned was the
    fact that the dynamo system involved was *completly useless* when the
    cycle was not in motion.

    So you say. But there is no indication that the battery systems of
    the time would have made any difference, given that the incident as
    described shows the driver coming from the side.

    Quoted message said:

    Go ahead and bang on and on about how it was soley the driver's fault.
    You just look more and more like a sad, self deluding fanatic.

    So you say. And in truth I am a fanatic. I am fanatically opposed to
    blaming cyclists when negligent drivers kill them, especially on the
    grounds of safety choices they have made based on the best information
    available at the time.

    That something "sounds very dangerous" does not mean it is, and even
    if it were to increase the risk, that will *never* excuse a driver who
    is simply not looking where he is going. It's right up there with
    "aggressive" street furniture and "dangerous" trees in the litany of
    cager evasions.

    Guy

    Normally I agree with most of Guys posts, but this is because they are
    generally well reasoned arguments backed up by research. In this case I
    have to side with Steven against Guy's kneejerk, fanatical, 'bike-is-
    right', anti-[censored]-behind-the-wheel post.

    It is laughable to expect (as Guy stupidly seems to) us to see and avoid
    an unlit person at night. When travelling through a junction at 60mph
    there is often not enough time to react to stationary objects appearing
    in the headlights. How can this be the fault of the driver?

    Guy; either grow up or learn to drive responsibly.

    --
    This post has been carefully constructed over many seconds so as not to
    require a smiley. Please take a commensurate amount of care in the
    reading as was taken in the writing.

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