Valkyrie wrote:What I'm thinking mdmf007 is looking at is a rectified generator, (lets not get into the semantics of generator/dynamo/whatever. It's all the same thing for our purposes.) although the loss from rectification is probably not worth it because if you're running incandescents, as stargeezer points out, they don't care what direction the current is coming from or how fast.
If you want to run anything other than a dumb light bulb it gets funny. The stuff coming out of the wall is a nice 60 hz regular sine wave. On your bike, you're running at the frequency your bicycle tire spins. It's a nice sine wave since that's the way it works, but probably not a stable frequency. For anything other than incandescents, rectifying it (turning it to DC) makes sense because then you can do some fun and interesting things with voltage regulation much more easily to keep those lights burning even when you stop for someone to pass.
LEDs are most efficient with DC, but as stargeezer pointed out, they'll work with AC too. Some diodes (which LEDs are a sub-class of the light-emitting variety) are not very well built for reverse currents and will break down (although "break down" is a relative term and is sometimes intended) if you run them backwards. It's been years since I paid attention to that, so it might be a thing of the past.
Chances are you have no voltage regulation at all on your generator. Do the lights go off immediately when you stopped moving? If it's a cheapie sort of generator, where the output directly drives the light, then chances are it's spiky all over the place.
Either way, a nice rectifier circuit that provides a little regulation (capacitance: it takes the spikes out!) will go a long ways.
(And yes, I DO have a BSEE, so I'm not totally talking out my ass.)
LED Lighting Help
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stargeezer
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It would appear to me that mdmf007 must have read what he expected and not what was written.Valkyrie wrote:Uh, dude. That's pretty much the opposite of what I said - if you just slap it on there your lights will all burn out, like he experienced...
Oh, and despite the fact that I'm an engineer-geek, I'm a girl-type person. grin
Being another geek, I would choose to use the generator with a small rechargeable battery or large capacitor, but using a larger battery that would last the week would be easier for someone without electronics skills.
If you really want to use a generator, I would suggest a PM to either myself, or Valkyrie if she is willing to help. Either of us could make your results with that generator much better for next year.
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Teo del Fuego
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wow, thanks everyone for your help and info. Very much appreciated.
My LEDS were, indeed, wired in parallel. I used an on-line resistor calculator to determine what type of resistors I needed based on an assumed 6v output. (Each LED had its own resistor.) My generator cost $9 at Target, which included headlight and tail light and the lights go off immediately after the tire stops turning, so Im pretty sure the generator contained no capacitor.
Im still unclear about the Dynamo comment. Just so I wont keep staring at the ceiling all night, if electricity is generated by mechanical means, whether it be a dynamo or what, isn't it by definition AC unless, and until, something inside the generator-dynamo converts it to DC?
I love learning about all this stuff and I'll continue to explore and dig deeper. But the very practical side of me knows keeping it simple for this particular application and going with a battery is the way to go.
Thanks again everyone!
My LEDS were, indeed, wired in parallel. I used an on-line resistor calculator to determine what type of resistors I needed based on an assumed 6v output. (Each LED had its own resistor.) My generator cost $9 at Target, which included headlight and tail light and the lights go off immediately after the tire stops turning, so Im pretty sure the generator contained no capacitor.
Im still unclear about the Dynamo comment. Just so I wont keep staring at the ceiling all night, if electricity is generated by mechanical means, whether it be a dynamo or what, isn't it by definition AC unless, and until, something inside the generator-dynamo converts it to DC?
I love learning about all this stuff and I'll continue to explore and dig deeper. But the very practical side of me knows keeping it simple for this particular application and going with a battery is the way to go.
Thanks again everyone!
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mdmf007
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Yeah - I made some assumptions - and they were based on my experiences
http://www.bumm.de/docu/download/106e.pdf
My "Dymotec" model S6 produces 6 volts at 3 watts at 55% efficiency so claims the literatire. I got it at walmart for 13 bucks. Its output is in DC so thats the assumption I was making.
I am still thinking that a battery would be the simplest setup of all. You can get led christmas lights on a string with a battery pack at Target rather cheaply, with controls even. Modifying one of them would be very simple.
just my 2 cents
http://www.bumm.de/docu/download/106e.pdf
My "Dymotec" model S6 produces 6 volts at 3 watts at 55% efficiency so claims the literatire. I got it at walmart for 13 bucks. Its output is in DC so thats the assumption I was making.
I am still thinking that a battery would be the simplest setup of all. You can get led christmas lights on a string with a battery pack at Target rather cheaply, with controls even. Modifying one of them would be very simple.
just my 2 cents