Re: For those who believe in electricity

On Wed, 9 Apr 2025 12:35:15 +0200, Rolf Mantel <news@hartig-mantel.de>
wrote:

Am 08.04.2025 um 22:12 schrieb sms:

On 4/7/2025 5:15 PM, Jeff Liebermann wrote:

>

Not going below 0V is the most common way PWM is used.  However, it's
not mandatory or the only way:
<https://en.wikipedia.org/wiki/Pulse-width_modulation>
Note that the waveform shown goes below 0V.

Yeah, that is true, it's possible for PWM to go below zero, but that's
not the way it's normally used for LED light dimming or PWM fan speed
control.
 
With LED bicycle lights, it's surprising that no bicycle light company
has a dynamo input into their battery powered lights. Even at only 3W
from the dynamo, you could power a high-end bicycle light at lower
power, and you could be charging the battery during daytime rides when
all you have on is the daytime running light.

>
"No" is a not quite correct, "extremely rare" would describe the market
better.
<https://nabendynamo.de/produkte/scheinwerfer/ladelux/>
>
Slightly more common: a "dynamo driven power supply" produces power to a
USE output, and theoretially you can route that USB power into your bikt
light but with no fine-tuned optimization the output is too low to make
it worthwhile in any sense.

This article shows 26 such bicycle USB chargers.  That seems to be a
popular use for bicycle dynamos.
<https://www.cyclingabout.com/list-of-hub-dynamo-power-supplies-for-usb-devices/>


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Jeff Liebermann                 jeffl@cruzio.com
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