Electronics, Lighting, & Gadgets - disc brake MOUNTED generator?

Are there any generators available which will attach to disc brake mountings (by basically using the rotating disc to generate electricity)? I don't mean a regenerative brake, but just something that can be driven by the disc like the bottle generators which are driven by the tire.

My rear hub can accept disc brakes, but I'm not using it and my front hub can't be replaced with a dynamo hub because it's special.

I know I could mount a tire driven generator, but it seems that a disc driven one would be better.

haven't heard of anything like it.

there are disc tab equipped generator hubs like shimano nexus however.
http://bike.shimano.com/publish/content/global_cycle/en/us/index/products/0/nexus/product.-code-DH-3D71.-type-.html

Is this what you're talking about?

http://farm4.static.flickr.com/3160/2349394239_446a07b628_b.jpg

Is this what you're talking about?

I'm not sure...but I think it might be because that thing pinching the disc doesn't look like a brake pad.

Do you know where I can find more information on how to build one?

the generator is inside the hub, which is why they're so big.
the disc is part of the disc brake assembly.

I haven't heard of a rear wheel generator hub, if you want one for the rear.

That's a BB7 caliper, it has a pair of brake pads in it.

http://farm4.static.flickr.com/3074/2349388437_51109a4d8e_b.jpg

That's a BB7 caliper, it has a pair of brake pads in it.

Then, no that's not what I'm talking about.

I'm not interested in a disc brake, but an external dynamo which mounts to a disc brake compatible hub and dropout.

there are spoke mounted dynamos which, from what I've heard, are the predecessor to dynohubs.
I've also heard, from the same guy, they're not too great in terms of water resistance or power output.

no idea where you can get some.

Then, no that's not what I'm talking about.

I'm not interested in a disc brake, but an external dynamo which mounts to a disc brake compatible hub and dropout.

Don't think anything like that exist. Unless you mean drum brakes or roller brakes.

Hmm...

How do you mean, your front hub is "special"? If it's an emotional attachment, put it under glass ;) and get a dynohub. If it's a mechanical compatibility issue of some kind, like it's the only hub that fits in that fork, then it'll be difficult at best.

I suppose that you could get a rear hub with a disc rotor and adapt a bottle generator to run against it. It wouldn't drag as much as if it were using the tire sidewall because the leverage will be more in your favor. But then again, it'll be turning at a substantially lower RPM than it's designed for, so it won't be putting out nearly as much power as you'll expect. It might not even give enough to power a headlight.

There are, or have been, crank-driven generators. They only work when you pedal, but they don't require replacing either wheel hub.

*edit* Well, I thought that I saw something about such generators at one time. I probably got confused about bottom bracket-mounted generators, which are a lot like bottle types except for where they're mounted.