How's the PWM on mode #1 of your BLF AA-Y4E?

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sb56637
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How's the PWM on mode #1 of your BLF AA-Y4E?
I don't notice it at all
47% (9 votes)
It's perceivable but doesn't bother me
37% (7 votes)
It's noticeably irritating
11% (2 votes)
It drives me crazy
0% (0 votes)
Oh, that's PWM? I thought it was a strobe!
5% (1 vote)
Total votes: 19

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Edited by: sb56637 on 11/25/2010 - 23:15
old4570
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Its there , but I guess Im old enough not to notice !  

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mizjif
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Not going to lie. I notice absolutely zero on mine. 

midieval10
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I have the J4 and the BLF and I don't notice any PWM. My camera picks it up though.

fishinfool
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I can barely see it but it really doesn't bother me too much since I rarely use the low modes.

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ezeqdb
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mine was sent 11/04 and I didn't receive it yet Sad

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agenthex
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It's not really a problem. PWM looks to be about a few hundred hz.

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sb56637
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Hmm I either received a really low-frequency sample or my eyes/brain have a really high sample rate.

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Don
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sb56637 wrote:

or my eyes/brain have a really high sample rate.

 

Love it!

 

Actually, the Vf of the LED probably will have some effect on the PWM frequency. My first thought was that it ought to be a fixed frequency, regardless of the LED, but the world tends not to be like that.

 

Maybe someone who knows about electronics could comment?

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

agenthex
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It's a fixed frequency. It's driven by the microcontroller which generally has an internal clock. The pwn drive frequency is set as a divider on that frequency. It's not as accurate as an external crystal, but the variation is very small in human terms.

 

My "metric" for determining frequency here is to just shake the light vigorously. On the BLF, I can make out the hotspots, but only just. If we do napkin math, assume cyclic frequency of ~3hz, and I guess around 30 spots visible per half cycle (this number may be off because I really can't remember, and they're linked together anyway, but someone else better at counting can verify this), that's about 200hz.

 

Also, admin, pwm frequency doesn't change for lower modes, it's just more visible because the on-periods are shorter so the hotspot images are more discrete and thus don't streak/blend together as well.

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sb56637
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agenthex wrote:

Also, admin, pwm frequency doesn't change for lower modes, it's just more visible because the on-periods are shorter so the hotspot images are more discrete and thus don't streak/blend together as well.

Interesting, thanks for clearing that up for me. But even so, it seems to me that "frequency" is the correct term for the differing on-periods of the different modes, right?

 

So do you don't think it's likely that I received a sample with a significantly shorter on-period on low compared to what most of you received?

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agenthex
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Frequency has "1/time" units. It literally only means how many instances of occurance over a given period of time.

 

I don't know if the one you have is different. You can try estimating the frequency on yours like I did, and see if it's that different. In generally, I can only see the spots if I shake quite diligently, and a flashlight rarely gets used like that.

 

For comparison, the most evident instance of pwm is on my 3-mode MRV, I can see the discrete spots seperately if I move the light quickly from point to point.

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