Zebralight SC5 (1xAA, XM-L2) Review: RUNTIMES, BEAMSHOTS, VIDEO and more!

Jida

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Sep 16, 2009
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I have quite a few of the ZL AA lights. This one is on the short list to get however as others have suggested, a 2AA would be a no brainer. Especially if they added a momentary forward clicky switch on the back. Would be an excellent field light.
 

KeepingItLight

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May 25, 2015
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Hi selfbuilt,

Would you please comment on the oscillating output that CPF member maukka measured on his ZebraLight SC5Fc? Have you observed anything like it on the SC5 you tested?

PWM
PWM is used to control output on all modes except H1. The PWM is not visible to the eye, because of its low amplitude, but possibly shows up on camera. The cycling frequency is higher on higher output modes and ranges from 775 Hz to 5000 Hz. The amplitude however is higher on the higher modes.


TSHoFqZ.png

Oscilloscope screenshot at H2 ("81 lm").

Ioxjbn9.png

Zoomed in.

See the whole album of scope screenshots here:
http://imgur.com/a/IbSg6

This may be a sort of PWM that does not drive the emitter current all the way to zero, but instead oscillates between a high and low value. Since the light never turns off completely, this kind of PWM may induce little flicker. Maukka, himself, asks whether this sort of modulation should even be called PWM:

Because the output never drops to zero like in a traditional PWM, it is very difficult if not impossible to see with the naked eye. I cannot see it even if I wave the light itself or my hand in front of it like a madman.

Does someone know if this sort of low amplitude modulation is actually even called pulse width modulation or is it something else altogether?

CPF member scs notes that specs for the SC5 omit any statement to the effect that, "All levels are regulated using constant current." Do you think we can read anything into that omission?

The specs for it don't say, "All levels are current regulated."
In fact, NONE of the SC5 model specs say that, so they all use PWM at all levels other than max?
The catch is typically in the fine print, but in this case, it's what the fine print DOESN'T say that's important to notice.

Thanks for your attention.
 

amanichen

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Apr 23, 2006
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Virginia
Hi selfbuilt,

Would you please comment on the oscillating output that CPF member maukka measured on his ZebraLight SC5Fc? Have you observed anything like it on the SC5 you tested?



This may be a sort of PWM that does not drive the emitter current all the way to zero, but instead oscillates between a high and low value. Since the light never turns off completely, this kind of PWM may induce little flicker. Maukka, himself, asks whether this sort of modulation should even be called PWM:



CPF member scs notes that specs for the SC5 omit any statement to the effect that, "All levels are regulated using constant current." Do you think we can read anything into that omission?



Thanks for your attention.
Isn't this perhaps the ripple from a switch mode boost circuit? PWM is completely on/off, but I think most boost circuits have an internal switching frequency inherent in their design: http://electronics.stackexchange.co...frequency-have-on-a-switching-booster-circuit
 

selfbuilt

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May 27, 2006
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Would you please comment on the oscillating output that CPF member maukka measured on his ZebraLight SC5Fc? Have you observed anything like it on the SC5 you tested?
This may be a sort of PWM that does not drive the emitter current all the way to zero, but instead oscillates between a high and low value. Since the light never turns off completely, this kind of PWM may induce little flicker. Maukka, himself, asks whether this sort of modulation should even be called PWM:
Isn't this perhaps the ripple from a switch mode boost circuit? PWM is completely on/off, but I think most boost circuits have an internal switching frequency inherent in their design: http://electronics.stackexchange.co...frequency-have-on-a-switching-booster-circuit
That pattern is definitely not consistent with PWM. I have seen many oscillating signals like that over the years (on current-controlled lights). They are rarely intense enough to be detectable visually (except perhaps when shining on a fan or running water). Sometimes they are, which people mistakenly put down to PWM. I am unclear as to source of them, but it does seem to be intrinsic to many circuit designs.

In the case of my SC5, I didn't detect any on my oscilloscope with my sample. The above may simply be variability between lights, or differing sensitivity thresholds among oscilloscopes. As always though, it comes down to whether or not it is visually detectable. These sorts of signals do not appear to affect efficiency.
 

markr6

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Jul 16, 2012
Messages
9,258
I've been keeping my SC5w OP in my Jeep for a few weeks now. With a fully charged 2000mAh Eneloop, I noticed the voltage indicator will only give 1-2 flashes when it's cold (sitting in ~40°F weather all day). When it's warmer, it will flash 4 times.

Do you think this is the battery, the electronics in the light, or a combination of both? I guess I can test this with my refrigerator sometime.

To complicate it even more, sometimes when cold and giving 2 flashes, I loosen the tail cap and re-tighten it which will make it go back up to 3 or 4 flashes. I'm not sure what that's about.
 

newbie66

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Mar 2, 2013
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Malaysia
I've been keeping my SC5w OP in my Jeep for a few weeks now. With a fully charged 2000mAh Eneloop, I noticed the voltage indicator will only give 1-2 flashes when it's cold (sitting in ~40°F weather all day). When it's warmer, it will flash 4 times.

Do you think this is the battery, the electronics in the light, or a combination of both? I guess I can test this with my refrigerator sometime.

To complicate it even more, sometimes when cold and giving 2 flashes, I loosen the tail cap and re-tighten it which will make it go back up to 3 or 4 flashes. I'm not sure what that's about.

I sometimes loosen and re-tighten my SC5 too for a more accurate reading. I find it odd as well. Seems like getting an accurate reading off a Nimh is difficult.
 

rexet

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Sep 21, 2012
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Thank you for this great review Selfbuilt!
You convinced me to spend $69 on my forth Zebralight flashlights (I already own a SC600 MKII and a pair of SC52)... that I really don't need :grin2:

I placed my order at the Zebralight online store. It is currently on back order, I can't wait.
 
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paojerokid

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Sep 22, 2016
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Where is the sc5 available? Its still on backorder at zebralight website.

(Is the sc5 still the current model or theres an updated model already? Is it still the brightest at 500lumens for a single AA or other brands already released a better or equal competition to the sc5?) Thanks.
 
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GarageBoy

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Jun 12, 2004
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Brooklyn NY
Looking at this review as zl is coming out with a mkii - did I misread these runtime charts? Is this thing almost as efficient as a bunch of 2xaa lights while only using one?!
 
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