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Thread: Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

  1. #1

    Default Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

    I find even my mid price front Stzvo LED flickers at walking and low cycling speed now that it is powered from a hub and not a bottle 'dynamo':

    As I think it would be better for front LED lamps not to flicker so much (after all in the UK battery lamps are strictly limited to a simple 1-4Hz flash range of fixed mark-space ratio to limit discomfort to epileptics) , what is a commercially acceptable way to do so, supposing that the Stzvo put their foot down a bit or merely tried to encourage reduction of low speed flicker:
    eg
    1) Cleverer switch mode circuitry (eg using a microcontroller rather a dedicated switcher IC)?
    2)Have a connector on lamp that allows an extra external smoothing capacitor to be added (because fitting such a large physical size capacitor in the lamp would make the lamp to big)?

    etc?

  2. #2
    Moderator Alaric Darconville's Avatar
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    Default Re: Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

    Quote Originally Posted by aahhaa View Post
    I find even my mid price front Stzvo LED flickers at walking and low cycling speed now that it is powered from a hub and not a bottle 'dynamo'
    The hub dynamo probably produces AC, but even if it is rectified it'll be a pulsed DC, with a lower frequency at lower speeds-- speeds at which a tire-driven dynamo would fail to light many lamps. Maybe adding a capacitor bank would help smooth out the pulses and prevent deep dips, making it a bit less-flickery.

  3. #3
    Flashaholic Marcturus's Avatar
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    Default Re: Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

    Quote Originally Posted by aahhaa View Post
    I find even my mid price front Stzvo LED flickers at walking and low cycling speed now that it is powered from a hub and not a bottle 'dynamo':

    As I think it would be better for front LED lamps not to flicker so much (after all in the UK battery lamps are strictly limited to a simple 1-4Hz flash range of fixed mark-space ratio to limit discomfort to epileptics) , what is a commercially acceptable way to do so, supposing that the Stzvo put their foot down a bit or merely tried to encourage reduction of low speed flicker:
    eg
    1) Cleverer switch mode circuitry (eg using a microcontroller rather a dedicated switcher IC)?
    2)Have a connector on lamp that allows an extra external smoothing capacitor to be added (because fitting such a large physical size capacitor in the lamp would make the lamp to big)?

    etc?
    Though I dislike jogger-speed flicker, (and disapprove of marketing this bug as an inbuilt safety feature,) I haven't heard of evidence that a commercial dynamo lamp's flicker ever harmed an epileptic person. Any actual case, be it in traffic or when looking into the lamp when testing or mounting it, should immediately be reported to get the word out.
    For a slightly higher frequency due to a higher number of magnetic poles per revolution, use a Shimano hub, not a SON one.
    Commercially acceptable? Ummm, tell the boss to redesign the lamp using more expensive, suitably-sized caps and featuring lower internal resistance? ;-) After a bit of charging, SON's Edelux II doesn't seem to flicker nearly as bad as some (unnamed) mid-price Stvzo lamps, and I don't think the Edelux is too big or has a microcontroller inside.

  4. #4

    Default Re: Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

    Quote Originally Posted by Marcturus View Post
    Though I dislike jogger-speed flicker, (and disapprove of marketing this bug as an inbuilt safety feature,) I haven't heard of evidence that a commercial dynamo lamp's flicker ever harmed an epileptic person.....
    Even if flickering doesn't cause a fit, I have read epileptics say it can cause them discomfort. NB I think an edelux is just a B&M Cyo in a nicer case.

  5. #5
    Flashaholic* znomit's Avatar
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    Default Re: Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

    A low powered battery light on the bars/helmet gives enough light to reduce the apparent flicker from the dynamo light at low speed.


    Last year I put a 1.5w hub (SHIMANO Deore XT DH-T780-1N) on my commuter with an Eyc and its fantastic for city riding. Blinks like hell at low speed which I see as a feature not a bug.

  6. #6
    Flashaholic Marcturus's Avatar
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    Default Re: Reducing/avoiding flicker in commercial front LED AC generator hub lamps:

    Quote Originally Posted by znomit View Post
    Last year I put a 1.5w hub (SHIMANO Deore XT DH-T780-1N) on my commuter with an Eyc and it's fantastic for city riding. Blinks like hell at low speed which I see as a feature not a bug.
    Please report any outspoken epileptic's comments. B&M Eyc has a nearfield-heavy, narrow beam, and I am too lazy to switch lights at city illumination borders. And it's so tiny I have always felt it could be provoking more SMDSY claims. For generous city flicker and iffy water resistance, I'd probably install one of the cheaper, and somewhat larger, Herrmans H-Black MR series lamps.
    https://herrmans.eu/products/front-l...ck-mr4-dynamo/

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