On Mon, 8 Oct 2018 08:53:19 -0700, sms
wrote:

On 10/7/2018 9:46 AM, Jeff Liebermann wrote:

snip

Nice. There's another difference. He had years of experience, while
you seem to be limiting yourself to what you can learn from a garage
full of old bicycles and parts. That works, to a point, but I think
you will do much better either working for someone else in order to
learn the trade, or working on a better class of bicycle. For bicycle
lighting, there is a difference between cheap junk and a light
designed specifically for a type of bicycle riding. Or, perhaps
building a clone of a high end bicycle light might be ummm...
enlightening. You can buy all the components on eBay. Never mind
what it looks like, build it in a wooden box.

Do not build a high-performance bicycle light in a wooden box!

The package might have an effect on cooling the LED and electronics,
but that's not an issue here, where a proper beam footprint and
battery life are more important. The exercise will be in optics,
current regulation, beam pattern optimization, measurements, testing,
and the reality of such mundane problems such as high resistance
battery contacts, lossy components, junk eBay electronics, etc. I
agree that thermal management is important, but that can be done later
or when a proper package has been designed. Think of it more like an
optical bench than a streamlined finished product.

Well, maybe you're right. Instead of a wooden box, substitute an
aluminum mini-box to take advantage of better heat dissipation:
https://www.google.com/search?q=cast+aluminium+box&tbm=isch
Or maybe a plastic box with a clear cover so he can better see what's
happening inside:
https://www.google.com/search?tbm=isch&q=plastic+project+box+clear+cover
Remember, the uglier the construction, the better it will work.

There's a reason why high-performance bicycle lights use aluminum
enclosures, the thermal solution is the most difficult part of efficient
electronics design, whether it's laptops, phones, mainframes, or bicycle
lights.

Yep. I've seen a few high power bicycle light prototypes with built
in fans to cool the LEDs. Also, one with an scoop air intake for
improved internal air flow. LED output is higher at lower
temperatures.

You might be amused with the various flashlight forums for the latest
in high fashion, errr... high performance lighting:
https://www.candlepowerforums.com
http://budgetlightforum.com
Copper packaging and cooling has been fashionable for about 2 years.
Never mind that a metallic copper finish is a worse heat radiator than
an anodized black aluminum finish. Of course, some of these are
copper plated or painted aluminum:
https://www.google.com/search?q=copper+flashlight&tbm=isch
Sometimes, the original reason for using copper is lost and the
fashion thing takes over:
https://www.edcforums.com/threads/show-your-flashlight-patina.127703/
Sigh.

Anyway, I would be quite satisfied if Emanuel Berg were to build
something resembling a bicycle light from scratch, measures the
lumens, lux, candelas, beam pattern, variation in intensity across the
beam pattern, power draw, operating temperature, and then improves the
design updating the measurements as he makes changes.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558