On Thu, 03 May 2018 06:46:07 +0000, Ralph Barone wrote:

bob prohaska wrote:
I finally caved and bought a Shimano dh-3n72 hub for use on my exercise
bike. It works fine, but the LEDs flicker quite noticeably at all
speeds. The circuit puts series trios of LEDs in inverse parallel
across the dynamo, so each trio lights on alternate half- cycles. The
flicker wasn't visible with the old Soubitez roller, because it was
working at about 6x higher frequency. The circuit is at
http://www.zefox.net/~bob/bicycle/schematic.gif The point of the design
is to eliminate rectifier losses, which are substantial at low voltage.

The new setup might be ok for fast riding. At low speeds and in traffic
I'm less sure I'll like it and fairly certain bystanders won't like it
at all, especially at night. As a DRL it certainly aids conspicuity 8-)

Can anybody point me to a discussion of what outfits like B&M use in
their dynamo-powerd LED headlights? I've searched intermittenly but
never hit the right keywords.

Thanks for reading, and any guidance.

bob prohaska




Three white LEDs in series probably needs nearly 10-12 V just to
overcome the diode drop. Try just two in series and see if that helps
things.

The schematic has only two LEDs in series for each polarity of the
generator output. Assuming the LEDs are rated for more than the
generator's maximum output, there should be lots of light at 6V
(2 LEDs @ 3V each).