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Old 08-27-14, 02:00 PM   #1
knightsbliss12
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is it possible to build my own dynamo system for my bike?

Wasn't sure where this fitted been wondering can I make my own dynamo for my bike using stepper motor ? If so how what would a need,or I you have any other ways of doing so let me no,I want it to power my bike lights on my mountain bike
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Old 08-27-14, 02:40 PM   #2
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You might want to post this to the electronics, lighting, and gadgets forum. Someone there may have already tried this:

Electronics, Lighting, & Gadgets

Short answer is yes, it's possible but might not be worth the trouble once you figure in things like mounting the motor to the bike, creating a circuit to keep the output within spec of the lights, things like that...

edit: oh yeah, especially durability.

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Old 08-27-14, 02:58 PM   #3
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When a Nordlicht bottle / sidewall dynamo is $28, why bother?
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Old 08-27-14, 03:03 PM   #4
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Is your name "McGyver" ?
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Old 08-27-14, 03:04 PM   #5
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When a Nordlicht bottle / sidewall dynamo is $28, why bother?
New skill under my belt its the whole curiosity of can I sort of thing,and I can get parts to do it for free
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Old 08-27-14, 03:10 PM   #6
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Ah good love the cheek but no I'm not MacGyver ,just like making things
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Old 08-27-14, 03:32 PM   #7
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If you are unsure then probably not .. how big is your machine shop?
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Old 08-27-14, 03:47 PM   #8
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Fairly big how come?
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Old 08-27-14, 09:05 PM   #9
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Ought to be easy enough. The basic criteria should be mechanical and electrical. Probably the power you can push into the motor is about the power you can get back out of it. There is also the question of volts & amps. You can always play with transformers or buck/boost converters or whatever if the voltage isn't what you need.

Mechanically, you probably want to make something like a bottle dynamo. Maybe you could figure out how to adapt a hub somehow but that seems awfully hard. Take a look at the bottom bracket generator photo here: Sanyo 6 volt bicycle Generators - that might be the easiest route!

A big issue will be protecting the generator from water and debris.

Should be a fun enough project, why not!
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Old 08-27-14, 09:22 PM   #10
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Straight forward in principle but I suspect you'll end making a series of improving prototypes as you learn the lessons already known by the makers of commercial units. Efficiency and ruggedness are key.
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Old 08-28-14, 08:10 AM   #11
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If you enjoy tinkering, then it would be great fun, and definitely something that can be done.

I used to be mildly interested in generator/dynamo lights, but since the modern LED lights can run 30 hours on a set of AA batteries I have no interest. I may feel differently if I regularly rode after dark.

However, as an objective, you could try to make the smallest/lightest setup since the power consumption of some LED lights is minimal... Another alternative is to find out how far you can cast a beam on a dark night making the road look like it is illuminated by the mid-day sun.

Personally, when I ride after dark, I have no trouble keeping my speed low to not out-ride the small CatEye headlight I use.
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Old 08-28-14, 09:47 AM   #12
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Quote:
how big is your machine shop?

Quote:
Fairly big how come?
If you plan to machine all the parts for the dynamo it will be useful ..




so,, how much current does the stepper motor put out when it is spun?

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Old 08-28-14, 10:30 AM   #13
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Do NOT use a stepper motor - the cogging torque.

A permanent magnet DC motor is an effective generator when spun - 85 - 95% efficiency is achievable. The problem is that the output voltage is directly proportional to the input speed. This can be solved electrically with a voltage regulator.

Probably the coolest thing would be (from Wikipedia):
Brushless alternators
A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless alternators may look like one unit but the two parts are readily identifiable on the large versions. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted on the rotor. Neither brushes nor slip rings are used, which reduces the number of wearing parts. The main alternator has a rotating field as described above and a stationary armature (power generation windings).
Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the exciter. This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC supplies the rotating field of the main alternator and hence alternator output. The result of all this is that a small DC exciter current indirectly controls the output of the main alternator.

You could use a rechargeable battery to provide to provide the current to the exciter, and keep the battery topped off when the bike is moving. A regulator circuit would keep the output voltage constant above some determined low speed.
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Old 08-28-14, 10:35 AM   #14
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Cool that's helpful,not sure I can get a strong light off my leds if I spin it with my fingers so figured id get more light if I wedged a spanner on for now to spin it fast as I could with no light but yet it lights up if I spin with fingers
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Old 08-28-14, 10:44 AM   #15
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What Is the best motor for the job ?

Last edited by knightsbliss12; 08-28-14 at 12:52 PM.
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Old 08-28-14, 06:09 PM   #16
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I'm willing to try any dynamo ideas ,seen a few using hard drive magnets would need a few magnets maybe something to hold charge for few mins at traffic lights,relays for magnet to pass to generate electricity dunno if u could use an old car relay?,would want it to be none flashing lights,pretty open minded on ideas
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Old 08-28-14, 09:52 PM   #17
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If I was to ever get into riding long distances and wanted power from my legs via generator to power lights or charge light batteries or charge my phone, I'd consider a bike-mounted nimh or li-ion cell or something as a buffer in the middle to be pretty much essential. Keep all the lights on, things charging for a minute or 60 if you stop. Have an input to charge this off of home/car electricity too so it's 100% when you set-out.
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Old 08-29-14, 03:32 PM   #18
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Stepper motors (something you would mount on a bike) will only run small LED's.It won't run real lights...At least I couldn't get it too.

It would light some of those multi led flashlights,but they are pretty weak...Good to-be-seen light.

Put your stepper motor in a drill and hook up your lights and see....

Get a car mag....
Turn it with a small motor and wire it to the frame when parked....You'll find anyone that touches your bike.....laying next to it......Works on cars too!

Last edited by Booger1; 08-29-14 at 04:06 PM.
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Old 08-29-14, 04:42 PM   #19
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I'd consider a bike-mounted nimh or li-ion cell or something as a buffer in the middle to be pretty much essential. Keep all the lights on, things charging for a minute or 60 if you stop. Have an input to charge this off of home/car electricity too so it's 100% when you set-out.
Modern lights have a capacitor for several mins of standlight when you stop
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Old 08-30-14, 03:57 PM   #20
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Hmmm any ideas on a contactless dynamo ??
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Old 08-31-14, 07:15 AM   #21
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Also after hooking motor up to a drill I got 10.6 volts
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Old 08-31-14, 06:48 PM   #22
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Working on a hard drive magnet and hoping a car relay would work on an induction power I think
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