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Thread: Dyno light test rig...

  1. #1

    Default Dyno light test rig...

    I don't have a suitable regulated power supply so I've been meaning to put this together for a while - spare hub, sewing machine motor and foot pedal, aluminium channel from the parts bin and a nice piece of wood. Will make this winter's experiments much easier...

    Sam

  2. #2
    Flashaholic* Steve K's Avatar
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    Default Re: Dyno light test rig...

    Quote Originally Posted by samsavvas View Post
    I don't have a suitable regulated power supply so I've been meaning to put this together for a while - spare hub, sewing machine motor and foot pedal, aluminium channel from the parts bin and a nice piece of wood. Will make this winter's experiments much easier...

    Sam
    Not bad! Maybe put a layer of tape around the hub shell to protect it from the belt?
    Might need to build up the tape on one side to keep the belt from wandering off to the narrow (i.e. small diameter) part of the hub shell too.

    The spare hub does avoid the need to drive a complete wheel, which substantially reduces the size of the test rig... very nice! Plus, it reduces the odds of something getting caught in the spinning parts.

    So what are the plans for experiments??
    What sorts of things are you thinking about?

  3. #3

    Default Re: Dyno light test rig...

    Hi Steve,

    The Shimano hub has a convenient rounded groove in the shell that the 'belt' (just a large plumbing 'o' ring) sits in. Fortunately there's no sign of any tendency to wander at all, even at full speed.

    I want to improve my practical understanding of multiple LED use, the value of LED arrays, the use of various current 'amplifiers' (as used in some of Martin's circuits) and so on. I'm hoping that the little rig will make such experimentation much easier! For instance I've recently got hold of 3 Noctigon triple boards with red XP-Es and want to satisfy myself what configuration will work best as a dynamo tail light, maybe in combination with my favourite Phillips front light. ;-)

    I also want to revisit a 6-led light (2 x triples) I built a few of years ago. I've never really used it as I found I just didn't go fast enough to get it to 'fire up' in any useful manner. A redesign is obviously needed!

    Sam

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    Flashaholic* znomit's Avatar
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    Default Re: Dyno light test rig...

    Nice rig.

    I'm getting a 1.5w hub built up for a commuter ( Deore XT DH-T780-1N hub, eyc and secula for lights) so will probably redo my power curve measurements.

    My rig was big wooden circle on a power drill, upside down bike.

  5. #5
    Flashaholic* Steve K's Avatar
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    Default Re: Dyno light test rig...

    Quote Originally Posted by samsavvas View Post
    .....
    I want to improve my practical understanding of multiple LED use, the value of LED arrays, the use of various current 'amplifiers' (as used in some of Martin's circuits) and so on. I'm hoping that the little rig will make such experimentation much easier! For instance I've recently got hold of 3 Noctigon triple boards with red XP-Es and want to satisfy myself what configuration will work best as a dynamo tail light, maybe in combination with my favourite Phillips front light. ;-)

    I also want to revisit a 6-led light (2 x triples) I built a few of years ago. I've never really used it as I found I just didn't go fast enough to get it to 'fire up' in any useful manner. A redesign is obviously needed!

    Sam
    Excellent! There's nothing like running some experiments to really prove or disprove whether something will work.
    If you have a few meters, I'd suggest measuring the voltage and current out of the dynamo, as well as the frequency of the dynamo voltage. You'll be able to tell how much power the dynamo can deliver to the load at different speeds.

    Instead of measuring the dynamo frequency, it might be easier to a bike speedometer to monitor dynamo speed.

    What will you be using as a figure of merit to compare the different light configurations? Will you be able to measure the light output, or will it be sufficient to measure the power delivered to the light?
    Or maybe use switches to quickly run comparisons between the lights??

    Sounds like fun. Be sure to document everything and take plenty of photos. We'll be expecting a full report.

  6. #6
    Moderator Alaric Darconville's Avatar
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    Default Re: Dyno light test rig...

    You could also test the relative efficiencies of dynamos. Get a Kill-A-Watt meter and meter the power use so you know really how much human power goes into lighting the lights-- measure the motor input and compare it to the generator set output. I'm not sure of the "resolution" of the Kill-A-Watt but it might be able to identify a generator that's less efficient.

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