On Sunday, May 6, 2018 at 6:56:01 PM UTC-7, Frank Krygowski wrote:
On 5/6/2018 6:15 PM, James wrote:
On 07/05/18 03:01, Joerg wrote:


Note the three big 470uF capacitor in the schematic. That's the
"flicker reduction trick" :-)

Problem is, electrolytic capacitors do not live long in harsh climate
conditions such as the black light enclosure baking in the glistening
Arizona desert sun for hours every week or riding around the Klondike
in a harsh winter.

For me the only proper way of lighting a bicycle is with a
rechargeable battery.

Bull**** alert!

We all know how reliable rechargeable batteries are, especially in harsh
environments, right?

OTOH, here is an electrolytic cap from Vishay, that has a "useful life"
of 1,000,000 hours at 40C, and 8000 hours at 125C.

https://www.vishay.com/docs/28334/118aht.pdf

(The useful life approximately halves for every 10C increase.)

If the temperature inside the electronics enclosure was much more than
80C for most of the time the light is in operation (E.g. while you're
riding and the light has forced air cooling), the engineer ought to be
shot, and that still gives a useful life of over 62500 hours.

The bull**** alert was a bit redundant. It was Joerg, after all!

But it's nice to get the technical details. Especially on a tech
discussion group.

Not that I'm a huge fan of dyno light for all purposes, but I've seen a couple of annoyingly bright dyno DRLs on the paths recently. They were fork crown mounted, so I'm pretty sure they weren't battery powered -- and were either pointed up or didn't have cut-off. For someone looking for an all-day DRL, I think that would be the way to go.

-- Jay Beattie.