Fiets, I'm not arguing that they did or did not produce drag. I'm sharing the fact they were single wire does not mean they were AC or DC. This is simple engineering. It's also quite basic that one kind is not more efficient than the other, save a slight increase in drag with brushes. But if they were DC they SHOULD have had some provision for brush service.

With modern design techniques drag and efficiency should have become greatly improved even for the ancient design concept of an AC machine, but this has to do with engineering and materials science rather than the principles of AC or DC operation.

You can stick to your guns incorrectly for as long as you like, I'm not going to waste a lot of time on it.

You can test AC v. DC with a cheap Radio Shack multimeter. If you can spin the gen and it will only show a measurable DC voltage, it's a DC machine. Period. If you can only read an AC voltage, it's an AC machine. Period. It's the only test that actually makes sense. If you can show a photo if the one that tests as DC and your results you might have a case. But what you've said so far is not correct, both regarding wiring and efficiency.

Glad you like your hub dyno! I like my SON, too. I'm looking for another one for Mrs. Road Fan's bike.

These look great! I have considered hub dynamos but decided against them for all of the reasons stated here and on the link. What light are you using and how bright is it?

The light I am using is an older Spanniga which is pretty weak by current standards. I intend to upgrade that one of the new BM head lights, either Eyc or Cyo, they are really powerful.

Marc

I running B&M IQ CYO lights. (One is older, one is newer with that newfangled zone closer to the bike. Can't remember which is which because the names have too many letters. ) Compared to any incandescent light they are a real eye-opener, unless you look into them in which case they are a real eye-closer.

I'd add just one thing to RF's description. The B&M lights apparently contain a PIC or similar chip to reduce the light output slightly when the input voltage drops. After all, when you stop you don'pt need to see so much but you still need to be seen. I'd guess it is done with PWM. The effect is to increase the length of time the stand-light operates.

Thanks for the research shortcut guys.
After getting caught out by sundown helping a friend w/ a project last weekend I need to fit my town bike w/ modern-ish dynamo lighting that is there when I need it.

-Bandera

GRRRrrr! BF just lost my posting! Here goes reconstructing ...

I'm running a Luxos B with a SON hub. When I used Soubitez lately it was the old Schwinn one on my Trek, and a stand-alone Soubitez on my former Woodrup touring bike, with a B&M Oval lamp and a 4D fender taillight.

I'd agree with Jim that there is a pulse-width modulator in the headlamp, at least in the Luxos. That light gradually brightens the beam as night falls, phasing out of DRL mode into full night headlamp mode. I don't think it would be needed to control light dimming when the bike slows down, since the LEDS will naturally dim a bit when the voltage drops below a threshold. I also would not be surprised if there is a micro controller, since at least the Luxos seem to have a lot of logical functions built in.

As an FYI, on the IP CYO series the light output seems to be quite constant, independent of speed, even at high speeds (>25 on our tandem, for example). But once you (which is to say, I or we) stop the light output takes a distinct drop, clearly bi-modal. This isn't the result of voltage dropping but must be a design feature. In any case, though available current does affect LED output it isn't the preferred way to modulate an LED. PWM is the standard way to do that, so a small micro-controller would seem obvious. At least that's how I read the riddle.

However it is true that as the super-cap runs down the LED gradually dims.

The LED would also suddenly dim if the s-c was out of the circuit and the generator slowed suddenly. I'm not sure how the s-c voltage is managed, so I don't know if this happens. But as you say, if there isn't a decrease as speed decreases, perhaps the architecture you suggest is correct. I haven't noticed on my Luxos B.

I'm not saying dimming cannot be managed as you say or that it isn't managed as you say. I'm suggesting there'a another way of managing it than using software, which is to diode-OR the rectified and filtered generator output and the standlight energy store to a common point, or power bus, that has a higher voltage than the standlight. When the generator voltage sags, its switch (could be a MOSFET, a Schottky diode or a silicon diode) opens and the bus is fed from the standlight caps. Keep in mind I'm an old analog SMPS designer, so I still tend to think of analog solutions first.

But we are both imagining circuit designs. Neither of us will know how it is actually done without detailed investigation, and I'm not motivated to buy a family of B&M lights and dissect them, so this discussion should not go farther unless you want to collaborate on a design, perhaps an open-source LED headlamp controller design. Problem is, the real system benefits are in optics and light management rather than in power electronics and controls, so I'm not sure open source or DIY can improve significantly on what exists. I don't have any home optics software, at least, nor test equipment.

Thanks for the discussion.

Plus if I keep at this Bandera's post will be moved to Electronics.

Good posts, folks! Keep 'em up!

This is great; I may have to get one for my commuter. I still have some old sanyo and union generators that I need to dig out of my parts box and see if all the parts are still there.

That missing parts box is really bugging me, what I aware of that's gone AWOL:

Raleigh wheel covers
Eclipse handlebar bag
Schwinn Approved Marchal French made SS bottle dynamo kit
Cannondale spare tubular bag w/ tire
Avocet computer & kit
Blackburn front rack

Never sign the moving company's bill of lading w/o a full inventory count, lesson learned.
Now back to your regularly scheduled generator conversation.

-Bandera

I used to keep a box of missing parts, but it had so much stuff in it I never could find the part I was looking for. Or maybe it's because it had so few parts, I forget. Anyway, I can't find that box anymore. It went missing, just like that parts it contained.

jim,

What you might miss the most are the fabric toeclip covers for winter riding, alloy Christophe toeclips and the Binda straps that are AWOL.

-Bandera

Wait, I have the toeclip covers. I saw one on the garage floor a couple of days ago. It will only take a week or two to locate the other. How badly do you want them? We can negotiate a price. I can be reasonable, really just ask my ex-wife.

Marc

Marc,

Sorry, we don't do Winter here at all anymore, no real need but Thanks.
You wouldn't happen to have a pristine Schwinn Approved "Super Sport" generator kit instead?

-Bandera

No most of my parts bin falls into the "totally useless accessory" category. That's it's all in a box, or on the garage floor.

Marc

Got one setup on my Ranger 3-speed, an old Schwinn Approved setup with the round, metal, bullet shaped headlight. Have another on the shelf which is going to go on Maggie's (either) Schwinn Breeze (currently on the road), or Raleigh Sports (on the rack getting refurbished) once she decides which one she wants to ride regularly.

And I grab any and all generator setups and parts that I can get. Yeah, they drag on the wheel. They're nice to have on our Saturday night rides in tandem with a battery or rechargeable light set, that way if we're running out past the battery life we've always got the backup. And even in bike-friendly Ashland, VA I don't complain about having a double lighting setup.

And as for period correctness, I love them. One of these days, though, I've got to start messing with a Dynohub.

I think it's Marchal, not Marshall.

Correct! I still dig the Cat-face logo.

In our less than scientific but reasonable drag testing two bikes of the same type were assembled for customers on each side of a Park workstand, one w/ a Schwinn Approved Union generator set the other w/ the Marchal. Dynamos engaged both were spun up to whiz-bang top gear speed in the workstand and allowed to coast to a stop. Both put out bright headlight/taillights but the French Super Sport unit spun a good bit longer than the German generator, a win for Marchal.

-Bandera

Very cool! I'd like to see that between a Sanyo hub dyno and a Shimano or SON, but we'd need rollers or a drill/disk rim drive for the front wheel.

I have a fair collection of sidewall generators (dynamos) Have to get pictures up. Just purchased a brand new Nordlicht to use on my "Beer Bike". I have Cibe, Lucas, Union, Sanyo and a few others. Also have a two bikes with bottom bracket mount dyno's. Then there are the dyno hubs... they run the gamut from an early 1950's FG to a brand new S-A XL-FDD. The bottle dyno's came stock on at least 4 of the bikes I have, I have added them to a couple of others where the cost or the time/usage of a dyno hub wasn't cost effective.

Aaron

I don't have a good shot of the bottle dynamo, but I'm still using the original Soubitez unit on my Peugeot UE-8 with original factory fenders & lights. To be honest, not only do they provide minimal light, but the bottle dynamo doesn't get much grip on the rim and the plastic guard piece sometimes rubs up against the large cross tubulars I run on this bike, so I hardly ever use it. I'm not much of a night rider either.

A properly equipped machine straight from the factory, and still in service.
No doubt a modern LED headlight would remedy the dimness situation but why fix what ain't broke...?

PS
Nice chainguard.

-Bandera