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From: sms <scharf.steven@geemail.com>
Newsgroups: rec.bicycles.tech
Subject: Re: For those who believe in electricity
Date: Tue, 8 Apr 2025 13:12:50 -0700
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On 4/7/2025 5:15 PM, Jeff Liebermann wrote:

<snip>

> 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.