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Is there an updated Dynotest somewhere?
On 9/14/2017 4:43 PM, Radey Shouman wrote:
Frank Krygowski writes: On 9/14/2017 10:26 AM, Ralph Barone wrote: bob prohaska wrote: Sepp Ruf wrote: For Rob who might experience mental drag uphill from just having to see a big, heavy, non-laminated hub slowly revolving in the front wheel, the smallish Shimano DH-T780-1N, 1.5W 250mA class, might suffice[1] once he grows sick of the Soubitez. Best price I see is 96 euros a pair from CNC Hamburg on ebay, no overseas shipping available, though. http://www.ebay.com/itm/253093811841 [1] DRL does not require more than 100 lumens if you get the optics right. It's a bit puzzling how folks seem to excuse poor design in dynamo hubs when they're considerably more fanatic about optimizing every other part of a bicycle. In particular, the 3 watt standard is utterly archaic. Folks now are starting to use dynamos to power electronics, and I suspect most would opt for more than 3 watt lights if useful designs were available. I still don't understand why high-end builders like Schmidt don't use salient-pole armatures, which could be constructed from standard motor laminations (instead of the custom clawpole monolith used now). That would shorten the iron path dramatically, reducing reluctance, reduce the length of copper, reducing resistance. The performance gains can be traded for lighter weight, higher efficiency or higher power. Every motor builder in the world does it that way, why not dyamo hub builders? Maybe there _is_ a technical reason, but it certainly isn't apparent to me. The use of incandescent bulbs may have set the tradition, but it's certainly no reason to continue. At this rate I won't "get sick" of the Soubitez, I'll wear it out. bob prohaska Machine theory is a bit of a black art for me, but I suspect that the "less optimized" magnetics in hub dynamos provides the extra leakage inductance required to make it self regulate into a 12 ohm load. I fully agree that a less well regulated output plus a switching regulator could work very well with modern electronics. Is it feasible to use a switching regulator when you've got as much inductance as a typical hub dynamo? I'd have thought that causes problems. Happens all the time. Google "h-bridge", and notice all those diodes in parallel with the switching components, allowing current always to continue to circulate through some path. Typically the diodes are in the same package as the switching component, eg MOSFET. So spikes, etc. from switching inductors get to sort of bleed off through diodes? Is that the idea? Again, electronics isn't my thing. -- - Frank Krygowski |
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