On Tue, 17 Jan 2012 21:48:22 -0000, "Ian Field"
wrote:


"Nico Coesel" wrote in message
...
John Larkin wrote:

On Tue, 17 Jan 2012 12:49:23 -0500, "P E Schoen"
wrote:

"Jim Thompson" wrote in message
m...

Here you go...

http://analog-innovations.com/SED/Bi...ubSwitcher.pdf

[snip]

Anyone care to actually discuss this?

Paul
www.pstech-inc.com


If led's are so efficient that a couple of watts is enough, there's no
need to multiply the alternator current. No switcher, no transformer.
A rechargable battery is a nice idea, to have lighting when you're
going slow or stopped. Simple linear electronics is probably all you
need.

The tail light of my 15 year old bicycle uses a supercap to store
energy. It has enough storage to keep the led on for about a minute
after stopping. Ofcourse the tail light doesn't need to be very
bright.

I'd like to replace the front lamp with a led lamp though.


I bet whatever 'dynamo' you have is better than my old Sturmey archer AG hub
which would only shift 1.8W loaded by the specified bulbs.

Currently I use it to charge a 1.2Ah SLA battery which powers a pair of
current sensing flyback converters that feed to series chains of LEDs, my
design was published in Elektor a few years ago.

The subject of my post on SED that triggered this thread here by JT was a
request on whether better load matching an old SA 'dynamo' could squeeze
more power from it - the consencus seems to be yes.

My read on that is more of a maybe, let's try it.

The extra power going into the battery would be handy for occasional use of
a 3W star LED "main beam" for unlit sections of cycleway.

Nice recap on what you have and where you want to go. Some others lost
sight of that.

?-)