[chbot] Chchrobotics Digest, Vol 141, Issue 4
helmut.walle at gmail.com
Thu Jun 27 13:05:38 BST 2019
Many if not all do use PWM - you can see it when you are out in the
rain: the rain drops look like " - - - - -" for the 50% brightness
setting, and a continuous line for full on. It may just be possible that
those that go CW for full on do not emit a lot of RF on the "high beam"
setting... However, if they have a buck converter, then that would still
emit some RF. But I for one wouldn't bother with a converter at all, and
instead just PWM-feed DC straight from the battery through the LED. It's
cheap and easy, and unless optimisation for efficiency, also including
exploiting the battery's capacity as best possible, are important, PWM
works pretty well. Most of all it's cheap, and that surely must be a key
requirement for most of these lights.
There are some more interesting (and higher-priced) lights on the
market. For example, LED Lenser are proudly marketing some of their
lights as being dual-mode: they can do brightness control like pretty
much all the other brands, but you can switch them to an uncontrolled
mode where they gradually fade as the battery discharges - now I am not
sure whether that mode is PWM-free, though.
On 27/06/2019 11:40 PM, ceo at andygardner.com wrote:
> Many LED headsets have selectable intensity. Push once for full on,
> again for slightly dimmed, etc.
> $10 says the ones they have are using PWM for intensity adjustments.
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