# >>> PWM Frequency List <<<



## EngrPaul (Mar 5, 2007)

The following is a list of measured frequencies for various flashlights. This will be updated as people contribute.

Jetbeam CL-E (AA): *73 Hz* [Strobe mode is 8 Hz]
Jetbeam C-LE v1.2 (AA): *315 Hz* [Strobe mode is 8 Hz]
Fenix L0 multi-level series (AAA): *100 Hz* [Strobe mode is 8 Hz]
Fenix L2D Series (2AA): *NO PWM *[Strobe mode is 8 Hz]
Fenix P1D Series (123a): *NO PWM *[Strobe mode is 8 Hz]
Huntlight FT-01-XRE (2x123a): *186 Hz *[Strobe mode is 8 Hz]
Photon Freedom (2x2016): *185 Hz*
FluPIC v2.2: *195 Hz*
SafeLight SuperBright (9V): *1149 Hz*
Inova Microlight: *95Hz* 
ALX-233C 3xC 3W: *128Hz*
Streamlight Tasklights: (3AAA, 1AA) *189Hz* [Strobe mode is 3 Hz]
LED Logic Striker-VG: *150~180 Hz* [Strobe mode is 9 Hz]
Inova Microlight: *97 Hz* [strobe mode is 3 Hz]
Freedom X-light micro: *185 Hz* [strobe mode is 11 Hz]
HDS B42: Burst: no PWM, Primary: no PWM, Secondary: *1161 Hz*, lowest level: *448 Hz*
LiteFlux LF2: *7670 Hz*
Nuwai 654C and 352: *9910 Hz*
JetBeam MkIIX: *120Hz* [12/14/5 strobes]
Jetbeam MKII (no X) *95 Hz* [strobe mode is 14 Hz]
Rexlight 2.0: *94 Hz* [strobe mode is 10 Hz]
Dexlight X.1: *120Hz* [12/14/5 strobes]
Dexlight X.V: *73 Hz* [strobe mode is 8 Hz]
Jetbeam JET-u (AAA): *315 Hz* [Strobe mode is 8 Hz]
Photon Photon (AA): *197 Hz*

[The strobe numbers are for the intentional pulsting mode of the flashlight, not related to PWM]

For those of you who don't know what PWM is, it's "Pulse Width Modulation". Instead of the flashlight circuitry dimming the LED by supplying less power, it "pulses" the emitter on and off rapidly. So instead of supplying 10% of the power 100% of the time, it's supplying 100% of the power 10% of the time.

The assumption here is that the eye has enough persistence of vision to not notice the pulsing on and off.

The "dislike" of PWM is either (1) the frequency is too low, and persistence of vision isn't enough to remove the flicker by the viewer, or (2) there is relative motion between the flashlight / environment / viewer, in which a pulsing light becomes more obvious.

Consider the case of two flashlights which are waved in front of a camera on extended exposure. The top one (Fenix) has a slower PWM frequency. The pulses on and off are more obvious to the user. The bottom one (Huntlight) has a faster frequency. It's less likely to be objectionable to the viewer.







Again, the lower the frequency (Hz), the more noticeable the pulsing is.

How can frequency be measured? Well, if you don't have an oscilloscope, I have an easier method for you. If you have a digital volt meter with a "Hz" or frequency setting, hook an LED up to the leads and shine the flashlight on the LED in a dimmed setting (one step below maximum). LED's just happen to produce a small voltage when light is shined on them (somewhat like a stereo speaker can work like a microphone). Here is a picture of the setup, in which the meter is reading ".186 k Hz" (=186 Hz):






I found that the LED is not sensitive enough for measuring lower light levels. Perhaps a solar cell would work better(?)

The goal of this post is to collect together PWM frequency data for different flashlights for member reference.

Comments and suggestions welcome


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## Argon (Mar 6, 2007)

Hey could you messure the frequency of the strobe on the lod when you have a spare moment. Im guessin it's at around 10Hz or less.

Cheers.


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## JanCPF (Mar 6, 2007)

Excelent idea :thumbsup:


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## Art Vandelay (Mar 6, 2007)

Thanks EngrPaul. Could you please measure the frequency of the Surfire A2's PWM? I bet most people don't realize Willie Hunt's PWM engineering genius is behind the A2. https://www.candlepowerforums.com/threads/107943


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## selfbuilt (Mar 6, 2007)

Hi EngrPaul - excellent idea, and I'd second adding strobe data to the list.

I tried this technique last night, but couldn't get the setup to work with my DMM. When I hook the leads up to an LED, I can detect a voltage deflection in the presence of light (although it's not stable - shows a strong drift corresponding to the brightness of the light). But my Hz mode continues to read 0. I'll try again tonight with another LED, but I'm not sure what the problem is. Any thoughts?


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## EngrPaul (Mar 6, 2007)

I've added all the PWM data for flashlights I own. The Fenix AAA's all came in at 100 Hz on the button. I'll try to collect strobe data too, if possible.

selfbuilt- try using a different LED, maybe colors work too (green?) reposition things too. Make sure the light is straight at the lens so it converges on the LED chip. Also try swapping + and - leads. In the picture above the - is connected to the the cathode.


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## doc_felixander (Mar 6, 2007)

the frequency might just be too low for your DMM. i've seen only a few that have a range lower than 1kHz, and some just have a bad resolution/accuracy in the 1kHz range.


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## doc_felixander (Mar 6, 2007)

errr....on second thought it's more probable that your DMM requires TTL levels (>2,7V) for correct measurement on the frequency range, you might check that.


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## tebore (Mar 6, 2007)

Measuring an HDS would be interesting.


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## selfbuilt (Mar 6, 2007)

Hi EngrPaul & doc ... I suspect it's the LED (cheap white DX type used in fauxtons). I tried reversing the LED leads, to no effect. I also tried all the permuations my DMM allows for frequency/Hz measurements, including the alternate Hz~V setting for input scope >30V rms & <1kHz, all to no avail. My DMM is supposedly rated for 10Hz to 10MHz, so I suspect it's the LED. I'll try tonight with the coloured LEDs and see what happens.
[EDIT #1: I'm thinking it's possibly the signal requirement needed from the LED source - my DMM manual says I need >=200mV for Hz readings when on the Hz~V setting, and I don't think I was consistenly getting that from the LED. Not sure of the requirement for regular Hz setting, though].
[EDIT #2: Thanks Craig, I'll also try some of my colour LEDs tonight]


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## The_LED_Museum (Mar 6, 2007)

selfbuilt said:


> ...I tried this technique last night, but couldn't get the setup to work with my DMM. When I hook the leads up to an LED, I can detect a voltage deflection in the presence of light (although it's not stable - shows a strong drift corresponding to the brightness of the light). But my Hz mode continues to read 0...


Be certain that the LED you use is not a white LED.
Red, orange, yellow, or yellow-green LEDs would lend themselves well here.


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## selfbuilt (Mar 6, 2007)

Success! I used a red LED and was able to get stable Hz measurements.

Like EngrPaul, I've found only the highest intensity light levels would give a reading. I don't have the huntlight, but I can confirm EngrPaul's readings on the L0D-CE & C-LE.

JetBeam C-LE: 73.1 Hz on primary (aka medium)
7.66 Hz on strobe
Fenix LOD-CE: 99.8 Hz on primary (aka medium)
8.34 Hz on strobe

I tried the Streamlight tasklight 2AA, but intensity on low and strobe was too low to get a reading. I did managed to get a reading on my Photon Freemdom X-light micro:

Photon Freedom: 184.6 Hz on setting just below maximum
91.2 Hz on strobe mode
(doesn't make a lot of sense on strobe, but it oscillated a lot around 10-40 Hz before finally settling on 91.2Hz. May want to discount this one due to low light intensity?).

According to the voltage scale on my DMM, it seems I need a light to register ~0.6V intensity off the red LED before it gives me a stable voltage reading and allows Hz readings to be made. Below that, the voltage indicator sways madly, and no Hz reading can be made.


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## selfbuilt (Mar 6, 2007)

A few more for you:

Fenix L0P-SE: 99.1 Hz on primary (aka medium)
Fenix P1DCE: 8.03 Hz on strobe
Fenix L2DCE: 7.82 Hz on strobe

The LOP-SE on primary seems to be absolute lowest light intensity I can detect to get a Hz reading (0.6V exactly). You have to carefully align the LED right on the center of the lens to have a chance at a stable reading.

I'll try a few other color LEDs and see if anything changes.


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## EngrPaul (Mar 6, 2007)

Am I correct the L2D-CE doesn't use PWM? Please verify


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## EngrPaul (Mar 6, 2007)

Art Vandelay said:


> Thanks EngrPaul. Could you please measure the frequency of the Surfire A2's PWM? I bet most people don't realize Willie Hunt's PWM engineering genius is behind the A2. https://www.candlepowerforums.com/threads/107943


 
Are you asking me to measure the PWM of the incandescent bulb? I don't think you can do it externally because the filament stays hot between pulses. 

As usual, correct me if I'm wrong.


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## EngrPaul (Mar 6, 2007)

selfbuilt said:


> Photon Freedom: 184.6 Hz on setting just below maximum
> 91.2 Hz on strobe mode
> (doesn't make a lot of sense on strobe, but it oscillated a lot around 10-40 Hz before finally settling on 91.2Hz. May want to discount this one due to low light intensity?).


 
Do you think it's pulsing AND strobing at the same time?

I want to measure a safelight but I have to dig around for some colored LED's, 'cuz the white one ain't workin'


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## selfbuilt (Mar 6, 2007)

EngrPaul said:


> Do you think it's pulsing AND strobing at the same time?



I'm not sure what's going on with the Photon Freedom. As I said, the strobe readings would vary from 10-40 Hz, then suddenly lock at 91.2Hz. It's definitely a faster strobe than the Fenixes, but it's not that fast, it seems to me.

As for the P1DCE & L2DCE, I know they don't use PWM - but I was just trying to measure strobe frequency. 

It's a pity the SL-TL 2AA was too low intensity - I quite like the strobe freq on that light (lower than the Fenixes). I'll let you know if my other coloured LEDs do any different.


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## The_LED_Museum (Mar 6, 2007)

I do not own or have access to a DMM with Hz or frequency settings, so I cannot test in this manner. :shakehead:


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## selfbuilt (Mar 6, 2007)

Just tried green and purple LEDs - no dice. Seems only red is sensitive enough.

BTW, I approve of your limits on significant figures (or digits, as the kids say today). The numbers I report are given to the precision that the DMM reliably gives (i.e. I do multiple tests). Of course, who knows how accurate that really is - so I agree with your decision to limit the sig figs to whole numbers.

It's a pet peeve of mine how people like to report output, lumens, etc to several decimal places, when that precision is clearly not available in their own instrument (i.e. if they do repeated tests, there's no way they are reproducing that). Not to mention there's no way of confirming accuracy to a true value.

Well done on a fun exercise - I'm looking forward to seeing results on other lights.

P.S.: Can you measure the huntlight at one more intensity level down? I'm curious if different PWM freqs are used for different intensities - none of my lights have more than one PWM mode that I can detect with my setup.

[EDIT: on further testing, I think the problem with the SL TL-2AA is simply that the strobe rate is too low for the DMM to pick up. My Inova microlight is similarly undetectable in strobe mode, despite providing enough voltage intensity to register on the DMM. Both lights tend to strobe around ~3 Hz, according to my manual counting with a stopwatch]


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## EngrPaul (Mar 6, 2007)

The_LED_Museum said:


> I do not own or have access to a DMM with Hz or frequency settings, so I cannot test in this manner. :shakehead:


 
Sorry to hear that Craig. Here's one for $20. The specs are here and says Range=20KHz, Resolution=10Hz, Accuracy= 1.5% of reading / 5 digits, sensitivity .2V RMS and input max 10V.

Please put March 4, 2007 in your LED Museum as first date LED's were used as transducers in a PWM frequency measurement.


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## Art Vandelay (Mar 6, 2007)

EngrPaul said:


> Are you asking me to measure the PWM of the incandescent bulb? I don't think you can do it externally because the filament stays hot between pulses.
> 
> As usual, correct me if I'm wrong.



I don't know how to do it externally. I'll search for it, maybe the frequency has been published.


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## Doug S (Mar 6, 2007)

An oscilloscope probe placed near the front of the light may be able to pick it up via capacitive coupling.



Art Vandelay said:


> I don't know how to do it externally. I'll search for it, maybe the frequency has been published.


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## JanCPF (Mar 6, 2007)

Just measured my FluPIC v2.2 light at 195 Hz.

Jan


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## selfbuilt (Mar 6, 2007)

FYI, I just noticed EngrPaul that in your original post, the pic comparing the fenix and the huntlight gives a pretty good estimate of the difference between their PWM modes. I count 17 distinct huntlight head images, versus 9 for the fenix. That would mean the huntlight is cycling at 17/9 times the rate of the fenix, which if the fenix is 100, gives you ~189 for the huntlight. Seems pretty close to actual measurement!


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## greg_in_canada (Mar 6, 2007)

Great thread! I asked about the Fenix PWM rate way back when it was first announced. Now we finally know.

What frequency to the LED Christmas lights flash at?  Just joking, but that might be a good way to check that your LED and DMM are working properly.

Greg


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## Knighthood (Mar 6, 2007)

EngrPaul - Thank you for providing the data !! For PWM does bother my eyes.

I have a question for you. I have the Jetbeam CL-E (AA) flashlight and it seem the PWM HZ is different for each light level. Am I correct here ? 

Thanks !! :goodjob:

Shawn


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## doc_felixander (Mar 6, 2007)

i just dug up a great little tool.... great for those who don't own an oscilloscope or DMM with frequency counter. 
it's a software oscilloscope which uses your analog mic input as signal source (dual channel thanks to stereo). 
bandwidth seems to be up to 44kHz, resolution up to ~1,3 Hz (adjustable via the buffer size). 

as long as you only connect a LED, there's no risk. my Audigy seems to take max. 1V at the mic in, but any line-in sources work, too.
for safety and adjustability you should better build a buffered probe with an op-amp, this works for levels of max. 150V.

of course this can't compete with a REAL oscilloscope, but I don't have one here and measurements like these here are where it's simply useful.

http://www.electronics-lab.com/downloads/pc/001/

this is a newer version which is limited to 14 days. i won't post any cracks here, but there is one....you just have to search. i still might have an older, free version somewhere on my HD. 

i really like it!


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## EngrPaul (Mar 6, 2007)

A solar cell works much better than an LED! I pulled apart an old solar-powered calculator and used the collector.

Yes, the frequency of the JetBeam at both dimmed settings is the same. The lowest seems worst because it's "OFF" time is longer, so you're more likely to notice it.

I was also able to measure a SafeLight at 1149 Hz!


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## selfbuilt (Mar 6, 2007)

EngrPaul said:


> Yes, the frequency of the JetBeam at both dimmed settings is the same.


I thought so as well - I just took some pictures of the L0D and C-LE at various intensity settings (i.e primary & low modes), and consistently got between 7-8 C-LE ghost images for every 10 on the L0D. Nice to know you actually were able to measure it with the solar cell.

Great thread EngrPaul ... :goodjob:


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## doc_felixander (Mar 6, 2007)

Strangely, my FluPIC v2.1 reads 195Hz, too. I thought Kevin had doubled the frequency in the v2.2 FW....

for those who wanted to know, measuring a hotwire's frequency works, too. at least it works with an AC 20W halogen spot.


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## JanCPF (Mar 6, 2007)

doc_felixander said:


> Strangely, my FluPIC v2.1 reads 195Hz, too. I thought Kevin had doubled the frequency in the v2.2 FW.....


Are you sure it isn't a v2.2 you have? Does it have 10 levels (v2.2) or 20 levels (v2.1)

Jan


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## doc_felixander (Mar 6, 2007)

yup, it still has 20 levels and SOS EVERYWHERE. bought it about a year ago. 
i was a bit confused, too, but double-checked with a frequency generator.

i've abused it quite hard, so a new one is overdue anyway.


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## arty (Mar 7, 2007)

Anyone know the PWM frequency that Streamlight uses?
I have a Tasklight 2L and can't see it - unless walking in the snow.


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## wquiles (Mar 7, 2007)

EngrPaul said:


> Are you asking me to measure the PWM of the incandescent bulb? I don't think you can do it externally because the filament stays hot between pulses.
> 
> As usual, correct me if I'm wrong.


I believe you are correct - the incandescent bulb does not actually turn on and off completely with PWM.

I actually tested Willie Hunt's LVR PWM module in my bench here and here and found the PWM frequency about 250Hz or so (I was not trying to measure frequency at the time, but it was in this "range"). 

With Willie Hunt's LVR's, the actual voltage that the bulb see (also known as the RMS or average voltage - see second link, post#11 for details from Willie himself on how to measure this elusive RMS value!) was not accomplished by changing the frequency, but by varying the duty cycle of the ON/OFF pulses. So as the voltage of the battery was depleted, the LVR made the ON pulse wider and wider (still switching ON/OFF at the same frequency) until it was basically ON all of the time and the LVR could no longer regulate the output. The LVR then created some "warning" pulses (pretty long, so you can actually "see" them) to let you know the LVR was out of regulation. Not only this, but his LVR's also have a built-in soft start to almost completely eliminate bulb burn-outs (instaflash) when the light is turn ON and the bulb filament is cold. Simply a freakingly awesome design :rock: 

Will


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## goldserve (Mar 7, 2007)

JanCPF said:


> Are you sure it isn't a v2.2 you have? Does it have 10 levels (v2.2) or 20 levels (v2.1)
> 
> Jan



It depends on what brightness setting you are on I guess. It maybe not be the most accurate way to measure and a real scope is required. V2.1 would be in the range of 100 so 195 is almost doubling it =D


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## doc_felixander (Mar 7, 2007)

yup, i used that software oscilloscope. 
but since i still didn't completely trust it after i checked with a frequency generator, i approached the problem ghetto-style.....i took my digicam and took a photo of the moving light at 1/10 sec. exposure and counted 19 pulses. 
this was measured with both methods at different levels (between 1 and 5) - same results. 

@will: at lower frequencies, it works well. it depends a lot on the frequency and waveform i guess, knowing that a hotwire's brightness doesn't rise/drop in a linear way. 
what you describe is my perception of 'classical' PWM. the influence of frequency changes on the brightness would not be too big, you NEED to change the duty cycle for the whole brightness range. (this effect might be different with inductive loads).

but reading the LVR thread, i noticed that pictures of your oscilloscope show values between 127 and 306 Hz....maybe a combined circuit?


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## doc_felixander (Mar 7, 2007)

sorry, wrong thought...of course you can fully control it by varying the frequency, but you need a fixed pulse width. this changes the duty cycle, but it's not PWM.




doc_felixander said:


> a hotwire's brightness doesn't rise/drop in a linear way.



i mean its response curve. its non-linear 'afterglow', in comparison to a LED.


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## PEU (Mar 7, 2007)

Thanks EngrPaul, this explains why PWM has such a bad press lately and kinda confirms my post in this thread

These frequencies are indeed very low for PWM thus the flashing is visible if you sweep the flashlight in front of your eyes.


Pablo


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## nightrider (Mar 7, 2007)

Thanks. Very interesting. I tried the solar cell.
Now I know why the JetBeam C-LE's PWM is so annoying to me (73Hz)


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## RebelXTNC (Mar 8, 2007)

selfbuilt said:


> FYI, I just noticed EngrPaul that in your original post, the pic comparing the fenix and the huntlight gives a pretty good estimate of the difference between their PWM modes. I count 17 distinct huntlight head images, versus 9 for the fenix. That would mean the huntlight is cycling at 17/9 times the rate of the fenix, which if the fenix is 100, gives you ~189 for the huntlight. Seems pretty close to actual measurement!


 
Since the trail of pulses spans the entire image (I assume being shot on a "bulb" shutter speed setting), rather than the exposure time being constrained by a shorter shutter speed, then any difference between the count in the photo and the measured values could be accounted for with the difference in velocity, distance and angle to the lens between the two lights being swung in an arc with one "inside" the other. We need to build a linear multi-light mover to eliminate that question. (No jokes about moving the torches across the field of view at the speed of light either.)

I did some testing today too after reading this thread. Using a high brightness red LED with a clear case, I got the following measurements. With my DMM, I did have to pay attention to LED polarity.
The TM-115X 2xCR123 3W two-stage light doesn't use PWM for low (which I already knew). It doesn't pulse, but I just wanted to test its low mode.
The ALX-233C 3xC 3W three-stage light uses 128Hz for both medium and low. After the light warmed up it dropped to 127Hz.
The Streamlight 3xAAA and 1xAA Tasklights both indicated 189Hz. It was pretty difficult to get the 1xAA reading due to the dim light but it would lock right in on 189 every time if positioned with extreme precision.
For comparison to some other lights mentioned, my DMM indicated 97Hz with my L0P Special Edition in both standard and low. My Inova Microlight was 95Hz on low.
I could not get a reading on either the full-blue or blue-white Woods brand AC powered LED nightlights even though you can clearly see them pulsing when you move an object in their light and they are quite bright. I guess they are never completely off and it's just a 60Hz (or 120Hz multiple) AC power effect since they use only diodes, capacitors and resisters in their circuit. Perhaps I need to try a different color LED to be sure or try the camera test.
That's all the lights I own that have visible pulsing.


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## wquiles (Mar 8, 2007)

doc_felixander said:


> @will: at lower frequencies, it works well. it depends a lot on the frequency and waveform i guess, knowing that a hotwire's brightness doesn't rise/drop in a linear way.
> what you describe is my perception of 'classical' PWM. the influence of frequency changes on the brightness would not be too big, you NEED to change the duty cycle for the whole brightness range. (this effect might be different with inductive loads).
> 
> but reading the LVR thread, i noticed that pictures of your oscilloscope show values between 127 and 306 Hz....maybe a combined circuit?


The difference in values in the scope shots is due to the all too familiar problem with aliasing. The scope's built-in frequency counter only works well if the sampling used is good - in many of those shots where you see the really low or high numbers, there are far too many cycles for the scope to read properly so the display shows an incorrect value. If you look again, when there is far fewer samples on the screen, the frequency is about 250-254Hz. I am sorry that I was not clearer on this earlier.

I also tested the output of the LVR's PWM signal (which is in fact a true PWM signal - see wikipedia's link on PWM ) while I lowered the input voltage, and it was totally awesome to "see" the duty cycle increase until it got to 100% - it was "ON" all of the time, even though the frequency remain constant. Nothing like having a scope to "see" these cool circuits in action  

Now, please note that the LVR that I used/tested was designed and adjusted by Willie to run a MN21 bulb at 6.8V DC RMS - it is all too possible that for a different voltage/bulb/load Willie would select a different frequency, but my testing was done with the one/single LVR module, so I don't know if he does change the base frequency as well or not on other modules/configurations. 

As you can imagine, if the frequency were much higher or lower, the bulb might not see the appropriate DC/RMS Voltage, so I am sure the frequency is key. I am sure that the choice of freq. by Willie was based on lots of work/experimentation, based on how incandescent bulbs operate - they guy "knows" this stuff well :rock: 

I hope this helps 

Will


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## EngrPaul (Mar 8, 2007)

The LEDLogic Striker Runs between 150 and 160 Hz at dimmed settings, and about 180 Hz at full blast. Strobing is about 9-10 Hz.


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## Art Vandelay (Mar 8, 2007)

I read that in the past the HDS EDC had a visible flicker on the lowest level. They made a change and the flicker went away. The lowest level of a HDS EDC U60 is .08 lumens. That's not 8 lumens but point zero eight lumens. To get a good beam at that level is amazing. It occurred to me that maybe HDS used something similar to an idea I read somewhere at CPF. Basically, get the best of both worlds. Use PWM at the higher brightness levels, and use current regulation at the lower brightness levels. This way at the higher levels of brightness you still have the best tint (pleasing the tint sensitive). The lower levels of brightness will not have visible flicker (pleasing the PWM sensitive).


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## selfbuilt (Mar 10, 2007)

Hi EngrPaul ... just tried a calculator solar cell, and got a few more readings for you. It also confirmed the Jetbeam CLE was 73 at both medium and low.

Streamlight tasklight 2AA: 189.6 Hz
(strobe mode: 2.96 Hz)
Inova Microlight: 96.9 Hz
(strobe mode: 3.3 Hz)
Freedom X-light micro: 184.3-185.2 Hz, depending on intensity
(strobe mode: 10.74 Hz)

Pretty consistent with other reports, but good to get the lower strobe modes.
:twothumbs


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## EngrPaul (Mar 10, 2007)

selfbuilt said:


> BTW, I approve of your limits on significant figures (or digits, as the kids say today). The numbers I report are given to the precision that the DMM reliably gives (i.e. I do multiple tests). Of course, who knows how accurate that really is - so I agree with your decision to limit the sig figs to whole numbers.


 
It was more for ease of reading, lots of numbers tend to make it more difficult to read, without adding any more clarity/value to the information.

Thanks for your contributions!


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## selfbuilt (Mar 10, 2007)

Hi EngrPaul ... fyi, to clarify, my Photon Freedom X-light micro uses the same circuit as the regular Photon Freedom micro (according to the packaging), but doesn't have all the extras or all the modes available. Not surprising it has the same PWM frequency. It also has a lower strobe mode, but I can't get a reading on it. You can see the details here:
http://www.photonlight.com/

Keep 'em coming folks ...


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## Quickbeam (Mar 10, 2007)

Very cool. Got this to work using a calculator solar cell. LEDs don't seem to do it for my meter.


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## Tronic (Mar 10, 2007)

Art Vandelay said:


> I read that in the past the HDS EDC had a visible flicker on the lowest level. They made a change and the flicker went away. The lowest level of a HDS EDC U60 is .08 lumens. That's not 8 lumens but point zero eight lumens. To get a good beam at that level is amazing. It occurred to me that maybe HDS used something similar to an idea I read somewhere at CPF. Basically, get the best of both worlds. Use PWM at the higher brightness levels, and use current regulation at the lower brightness levels. This way at the higher levels of brightness you still have the best tint (pleasing the tint sensitive). The lower levels of brightness will not have visible flicker (pleasing the PWM sensitive).


My HDS B42 have the following PWM frequencies:

Burst: no PWM
Primary: no PWM
Secondary: 1161Hz
lowest level: 448Hz

Note: Secondary and lowest level are slightly changed from factory default. The lowest level is the lowest possible setting.


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## jackcselab (Mar 21, 2007)

A forum user in Taiwan use solar cell to mesure PWM freq. of LiteFlux LF2.

http://my3c.com/D5/viewthread.php?tid=6881&extra=page=1&page=2

The freq. is about 7670 hz. Maybe much higher than any other flashlight.


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## big beam (Apr 18, 2007)

I just mesured nuwai 654C and 352(the 2-123 5W light)using a 12V solar panel and got 9.91KHZ is that 9910 HZ?

DON


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## JJohn (Apr 23, 2007)

You might want to add data on the LiteFlux LF2. It runs at 7.8kHz.


Oops, sorry, I did not see the post just two up from mine by jackcselab.


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## EngrPaul (Apr 23, 2007)

I think I got em all through the last post.


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## Knighthood (Apr 23, 2007)

We'll need an new update for Jetbeam CL-E ver 1.2 His site said "New Thread, no more flickering beam". Also Lens: Sapphire crystal w/ internal AR coating. I dont think the older version has sapphire crystal len. This time I am going to wait for the review of this new version before I order it again . . . I actually love the small compact form of the flashlight but just hated the PWM. 

Site: http://emilionworkshop.com/oscommerce/catalog/product_info.php?products_id=154&osCsid=6b25d00c9c37506426b438a642042b23


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## selfbuilt (Apr 24, 2007)

Hi EngrPaul ... just got my JetBeam MkIIX from DX, so here's some more numbers for you:

PWM: *118-120Hz * (advanced mode: 118Hz at 20%, goes up slowly to 120Hz by 90%)
Strobe (general mode): *11.6Hz*
Strobe (advanced mode): 14.4Hz ("15Hz mode") and 4.8Hz ("5Hz mode")

A definite improvement over the 76Hz C-LE. Don't know if the new 1.2 versions are any better (I presume DX is selling the v1)


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## David_Web (Apr 24, 2007)

"LiteFlux LF2: 7670 Hz
Nuwai 654C and 352: 9910 Hz"

Sorry, I'm not gonna believe that. Unless the measurement was taken by a scope.
IIRC efficiency is going to be pretty bad when you want to have PWM at that frequency.
For static application it's ok but not for portable lighting. Why do you think everyone else is stuck at the normal horrible rate? It's certainly not because they can't do better (maybe it it but that's not the point) but it's because of efficiency.
But that is only from the top of my head.

btw are you sure that the dmm is only triggering once per cycle, else it will bisplay double the frequency at around 50%

I have lots of scopes but no PWM lights. Maybe Ill see if I can find the switching frequency of the lights I have.


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## Ty_Bower (Apr 26, 2007)

No Rexlight? Somebody's got to have a Rexlight and a frequency counter by now...


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## JJohn (Apr 26, 2007)

David_Web said:


> "LiteFlux LF2: 7670 Hz
> Nuwai 654C and 352: 9910 Hz"
> 
> Sorry, I'm not gonna believe that. Unless the measurement was taken by a scope.
> IIRC efficiency is going to be pretty bad when you want to have PWM at that frequency.




I will try to measure it with a scope but, believe me, the PWM rate of the LF2 is significantly higher than 1kHz. I did a test with rapid movement and a high speed CCD to check it myself. Not scientific, but good enough to convince me that no human could detect the PWM frequency of this light. Below is someone else's image from an earlier review of the LF2. See the review forum. The top light in the image is the LF2 the middle and bottom are other common small cree lights:







Its efficiency is amazing too. I did runtime tests that were very surprising. How about over 7 days with a L92 AAA at near the lowest (yet still useable) setting?


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## selfbuilt (Apr 27, 2007)

JJohn said:


> Below is someone else's image from an earlier review of the LF2. See the review forum. The top light in the image is the LF2 the middle and bottom are other common small cree lights:


FYI, according to that review thread, top light is LF2 (on 0.2% ??), the middle light is the JetBeam CLE (on low) and the lower one is the MkIIX (on 5%). I measured the PWM on those two JB lights as 73 Hz and 118 Hz, respectively. 

https://www.candlepowerforums.com/threads/154068


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## Ty_Bower (Apr 27, 2007)

Ty_Bower said:


> No Rexlight?


I found this nifty sound card o'scope software:
http://www.zeitnitz.de/Christian/Scope/Scope_en.html

Using a yellow-green LED off the front panel of an old Dell, I confirmed my Jetbeam C-LE is 73 Hz. I measured my Rexlight to be about 94 Hz on low and medium. On high, the Rexlight still seems to have a frequency component to it, but the frequency is very high - maybe 4 kHz or higher. The Rexlight is running on a 1.2 volt NiMH cell.

edit: More notes on the Rexlight - the fast strobe is 10 Hz (50ms on, 50ms off). The slow strobe (SOS, which isn't really SOS) is one 850ms pulse, repeated every 2000ms.




Further 'scoping of the high mode shows the frequency definitely varies depending on some as yet undetermined condition. Perhaps as it heats up, or maybe as the battery voltage begins to drop, the drive current (on high) starts to become constant, and the pulses (if any) can't be detected by this software 'scope. Here's a screen image where it appears the PWM frequency on high is about 2.6kHz. A couple minutes after this measurement was taken, the output of the light had flattened out, and no peaks were detectable.


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## David_Web (Apr 27, 2007)

That is interesting. They must use dimming internally in the circuit and output ether PWM or a relatively smoothed out constant voltage. It is probably made by a single IC.
This sounds like good news to me. If it does indeed use PWM it is a big step in the right direction if it also is extremely efficient.

Nice link to the program. The fact that it mentions NI is a big thumbs up.
The difference you see in frequency is probably caused by the flash not timing the sampling frequency of your soundcard. you can dee in your image that the resolution it not more than around 10 per cycle of the light, that makes it wary from around 8-10 in the pic.
Btw I believe that the "pwm" that you see on high is in fact the switching of the regulator. If you look at the slow strob you can see it there as well. Not sure why it changes tho. Maybe it is compensating to keep the current to the led constant when the battery voltage changes.


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## Ty_Bower (Apr 27, 2007)

I hope I didn't cause any confusion. My first picture is of the 10 Hz strobe. I didn't bother to post the slow strobe. The 'scope images don't portray an accurate image of the slow strobe. Remember the input to this 'scope is a PC sound card. It is useless for measuring DC voltage. The low frequency respose is starting to suffer even at 10 Hz. If you feed it a steady signal, the input coupling saturates and you get a zero reading. The slow strobe should appear as a square wave ~850ms wide, but instead appears as a tall positive peak that decays to zero, followed by a tall negative peak when the light turns off.

It's still a really neat piece of software. I've cobbled together a very crude photosensor out of the Dell's LEDs connected to the ends of a broken headphone cable. The 1/8" mini stereo plug fits right in the line in jack of my sound card. Just about anyone could probably duplicate my results and measure the PWM frequencies of their own lights. Later tonight I'm going to check my HDS and my Lumapower M3.


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## David_Web (Apr 27, 2007)

Yes but the image indicates that the on-time is "noisy" as it's pretty much green rectangles. Have you ramped up the scanning frequency to the same as the full on to see if it looks the same?

My guess it that it's still noise from the converter and that it changes depending on how much it needs to boost the voltage. Then the PWM can come in and change brightness.


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## selfbuilt (Apr 30, 2007)

The strobe software with a red LED wired to a dollar store computer microphone worked great - thanks for the heads-up Ty_Bower! :goodjob: 

Setup was easy - I just ripped off the head of the microphone, and wired the two exposed bare copper leads to the two leads from the LED (from an old photon clone). Sensitivity is excellent with my Audigy sound card. And the software is very easy to use.

I was able to confirm all my previous results taken with the DMM/LED or DMM/solar cell. In all cases, the sound card/scope/LED results showed variances of less than 0.8% to my earlier recordings, which is pretty impressive.

But this method also allows me now to confirm PWM freq and duty cycle for lower intensities (e.g. 5% modes, etc.) and slower strobe modes (e.g. 1 Hz) that my DMM/solar cell method wouldn't pick up. So far, no surprises. 

This is most clearly an excellent tool!


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## Ty_Bower (Apr 30, 2007)

selfbuilt said:


> Sensitivity is excellent with my Audigy sound card...


Yes, it is very sensitive. I was getting nowhere trying to use an LED connected to my DVM. With the software, it was very easy to get a useful reading off just about any light. I've tested my HDS lights.

HDS Basic 42
Lowest setting (programmed to be as low as possible) - 506 Hz
"Secondary" setting (programmed two clicks down from default) - 1.9 kHz
"Primary" setting (at default) - 15.8 kHz
Maximum setting (42 lumens) - can't measure

HDS Ultimate 60
Lowest setting (set as low as possible) - 300 Hz
"Secondary" setting (re-programmed ?) - 1.2 kHz
"Primary" setting (set three or four clicks down from max) - can't measure
Maximum setting (set at 42 lumens) - can't measure

I'm impressed at how well the sound card can pick up a signal from the HDS, even on its lowest setting. The HDS is _very_ dim on low. I'm also impressed at the high frequency the HDS light uses. I wish the Rexlights and Jetbeams had similarly high frequencies.

I also checked the PWM on my Lumapower M3. Although this thread suggests it uses PWM, I am unable to detect it. This agrees with what my eye sees. I'm very happy the Luma M3 doesn't use PWM.


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## greg_in_canada (May 8, 2007)

Has anyone measured the Fenix P3D, or is this a non-PWM light?

Thanks - Greg


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## Art Vandelay (May 8, 2007)

FlashlightReviews.com says the P2D has current regulation instead of PWM. My guess is the P3D will not have PWM either.


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## HiltiHome (May 14, 2007)

My Jetbeam MKII (no X) measured 95,3 Hz

Strobe: 14,4 Hz


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## selfbuilt (May 31, 2007)

Got my DX versions of the Jetbeam C-LE and MkIIX lights, and they are exactly the same as their JB comparables:

Dexlight X.1: *118-120 Hz*, depending on mode, same strobe modes as MkIIX (i.e. 14/5/10 Hz)
Dexlight X.V: *73 Hz* on primary (medium) and low, same strobe as C-LE (8 Hz)

Also received my Rexlight 2.0 from Kaidomain:

Rexlight: *94 Hz* on medium and low, strobe mode *10 Hz*


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## Tronic (Jun 26, 2007)

I just received a few lights from emilion 

Jetbeam JET-u AAA

med: 314Hz
low: 314 Hz
max: no PWM
strobe: 7.6Hz

Jetbeam C-LE v1.2

med: 315Hz
low: 316Hz
max: no PWM
strobe: 7.6Hz


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## HiltiHome (Aug 11, 2007)

My Hyperion CE-R measured:

low: 312 Hz
med: 312 Hz
high: no PWM
strobe: 7,6Hz

No visible flickering on med, but still little nerves on low.


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## HiltiHome (Nov 7, 2007)

My new WolfEyes Storm-X3-LED measured:

high: no PWM
med: 250Hz
low: 250Hz
Strobe: 20Hz

no visible flickering to my eyes, but noticeable when pointing to a fan


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## Phaethon (Nov 28, 2007)

*PWM efficiency*

Excuse me if i am hi-jacking this thread but it's the one with the most recent posts. 
I have been thinking on the pwm in-efficiency claims and i understand that they are based on simple math, calculating the lux output based on the average Ah with which the leds are driver. However, i see a fault in this reasoning, as the theory reaches a conclusion based on a continuous drive model -which derives by averaging the feed current- and a current feed TO lumens output. My point is, that we should be focused on the outcome of pwm driving as it is perceived by the human eye, not a lux meter. Therefore, i believe that at a frequency of 100Hz, the eye can only see continuous light that consists of full intensity bursts, which have -let's assume - 700 mah feed. Compared to a constant driving of 1000 mah, the light output perceived by the eye should be the same, because the eye can't average the light emitted in actual time but only in relevant time. A light meter might measure the output in less lumens, as it has the ability to take infinite measurement during the 100hz cycles. The human eye cannot and therefore the light emission seems identical. The practical outcome is that we have the same light with significally less heat production and battery drain. Any thoughts?


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## selfbuilt (Nov 28, 2007)

Hi Phaethon ... :welcome:

What you suggest may be true, but most of the discussion around PWM efficiency at CPF (in the non-technical forums, at any rate) focus on its advantages/disadvantages relative to constant current control for producing visually dimmer light. I think everyone is in agreement over the advantage of some sort of circuit-controlled dimming (as opposed to an inefficient resistor setup, for example).

To summarize the general view, current controlled circuits have the advantage of longer runtime for lower output levels (due to the fact LEDs are more efficient at lower current drive levels), and lack of visual strobing effect. PWM has the main advantage of simpler and smaller circuits (and cheaper?) with no tint shift due to the consistent current drive level. 

PWM typically gets a bad rap here since current-controlled lights win out over PWM in terms of runtime at lower modes. But some of the newer PWM lights with >1kHz show no visible strobing, removing that general complaint. :thumbsup:

It's a pity EngrPaul is no longer around to update this thread.  His input was always very valuable.


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## Art Vandelay (Nov 28, 2007)

selfbuilt said:


> It's a pity EngrPaul is no longer around to update this thread.  His input was always very valuable.


No longer around?

I have not heard anything. Did something happen? 

It's only been a month since his last post.


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## selfbuilt (Nov 28, 2007)

Art Vandelay said:


> I have not heard anything. Did something happen?


He posted a goodbye back in early-mid summer. Since then, he's only posted on the site half a dozen times or so. You'll notice all the pictures from his threads are gone too. I don't know why he left, but I do miss his input in the reviews and modding forums.


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## Phaethon (Nov 29, 2007)

selfbuilt said:


> Hi Phaethon ... :welcome:
> 
> PWM typically gets a bad rap here since current-controlled lights win out over PWM in terms of runtime at lower modes. But some of the newer PWM lights with >1kHz show no visible strobing, removing that general complaint.


 
Thanks for your prompt reply. The reason for my post is that i am finishing a project torch (literally :devil based on the edison edipower *20W led*. I had to source a 10-15 degree lens and have a housing (edison provides NO housing or lenses for their top-power led???) from solid aluminium machined, for the setup to obtain sufficient heat dissipation. For added piece of mind, i am using a pwm circuit (based on a 555 chip) to drive the 17.5V, 1 Amp led in order to reduce heat production. Tests are very encouraging and i have no significant heat buildup with great output. Please note that the edipower 20W has a nominal output of at least 700 lumens at 17.5 volts. I look forward to finishing the tests and post duration specs and photos in a separate thread.


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## elho (Sep 24, 2008)

Interesting old thread. 

Using a photodiode in photoconductive mode and a DMM I got the following results:

Jetbeam Jet-µ: *73 Hz* [Strobe is 10 Hz]
Wolf-Eyes Digital Cree P4 HO 3.7v-6.0v D26 4 mode: *495 Hz* [Strobe is 13 Hz]
Wolf-Eyes Digital Cree R2 WC low Vf HO 3.7v-6.0v D26 4 mode: *530 Hz* [Strobe is 14 Hz]

These results go along with my observations of easily noticeable low frequency PWM on the Jet-µ and unnoticeable PWM on the Wolf-Eyes drop-ins.
The results for the Jet-µ however do not go along with those already in the list. 
My Jet-µ neither has memory nor beacon and looks different than the one in selfbuilt's review, so being different versions would be an explanation. Or the DMM is fooled by the constant component in this setup or something.

I guess, I should dig out some red LED... :thinking:


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## EngrPaul (Sep 29, 2008)

selfbuilt said:


> It's a pity EngrPaul is no longer around to update this thread.  His input was always very valuable.


 
I apologize for being absent for quite a while. I don't think I could possibly catch up with a comprehensive list. Too many new lights while I was gone! :mecry:


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## elho (Sep 29, 2008)

EngrPaul said:


> I apologize for being absent for quite a while. I don't think I could possibly catch up with a comprehensive list. Too many new lights while I was gone! :mecry:


Well, you don't need to do all the work - I'd guess if you just update the list in the first post with the data from the later posts in this thread, people will notice and be motivated to measure and submit data about lights missing in the list just like I did.


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## Dissipator556 (Jan 2, 2009)

Would be interesting to know the strobe rates of the Gladius and Xiphos lights (they look identical to me in strobe rate), as well as my Nitecore Defender Infinity (which looks much slower than the Gladius rate). 


If I had the time to rig something up myself to measure them, I would make it a DIY project. Not enough time lately- anybody else know the strobe rates off hand?


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## elho (Feb 10, 2009)

elho said:


> Using a photodiode in photoconductive mode and a DMM I got the following results:
> 
> Jetbeam Jet-µ: *73 Hz* [Strobe is 10 Hz]
> Wolf-Eyes Digital Cree P4 HO 3.7v-6.0v D26 4 mode: *495 Hz* [Strobe is 13 Hz]
> ...



I meanwhile did and it gave the same results.


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## elho (Feb 10, 2009)

At a recent geocaching event that had flashlights as its major theme, I was able to check out the PWM frequencies of some lights:

Dereelight DBS V2 3SD: *37300 Hz*
Jetbeam Jet-III M: *4000 Hz*
Jetbeam Jet-III PRO Ultra: *51000 Hz always* (ie. also in high mode)
Fenix LD10 Premium Q5: *NO PWM*
Fenix LD20 Premium Q5: *NO PWM*
Fenix PD20 Premium Q5: *NO PWM*
Fenix PD30 Premium Q5: *NO PWM*
Fenix TK10 Premium Q5: *NO PWM*
Fenix TK11 Premium Q5: *NO PWM*
Lumapower D-mini Digital (medium): *10000 Hz*
Lumapower D-mini Digital (low): *9800 Hz*
Lumapower MRV-SK v1.1 (medium): *10300 Hz*
Lumapower MRV-SK v1.1 (low): *9800 Hz*
Lumapower MRV-SK Ultra: *NO PWM*
MicroFire L500R Challenger: *NO PWM*
MicroFire TL1R P7: *NO PWM*
Tiablo A9: *NO PWM*
UniqueFire HS-802 Cree R2-WC 2-Mode: *NO PWM*
UltraFire WF-500 3-Cree: *35000 Hz and constantly rising!?!*
Wolf-Eyes 6AF Sniper MC-E (medium): *170 Hz*
Wolf-Eyes 6AF Sniper MC-E (low): *165 Hz*
Wolf-Eyes SuperStorm Q5: *207 Hz*
ZebraLight H60: *NO PWM*

The UltraFire WF-500 3-Cree was weird, the frequency kept going up slowly. :huh: I didn't have the time (with such a bunch of other more interesting lights around ) though to sit it through and see whether it would stop at some point.


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## elho (Feb 10, 2009)

EngrPaul said:


> I'll try to collect strobe data too, if possible.



So did I for my lights and also at aforementioned event. However some results do not make sense, so I did omit them:

The measured strobe frequency of my "classic" D26 Wolf-Eyes drop-ins is 13-14 Hz, for the new Wolf-Eyes electronic in the MC-E and SuperStorm (with strobe hidden in "concealed mode") and the Microfire L500R I measured 24-26 Hz, ie. a higher frequency.
But when testing the lights outside and trying the usefullness of the strobe to find tiny reflectors (the main flashlight use-case for geocaching), we found the strobe of the new Wolf-Eyes/Microfire more useful as it (more exactly the light returned by the reflectors) looked slower, more blinking/pulsing in nature than the fast flicker of the supposedly lower frequency of my drop-in. :thinking:

A scope would be needed for a definitive answer, my guess would be PWM with varying pulse widths throwing the DMM off.
Either way there seems little point in relying on the strobe frequency measured this way to tell much about its nature.


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## elho (Sep 19, 2009)

Some results for my Luminus SST drop-ins by nailbender and a ZebraLight:

CustomLites Luminus SST-50 3 mode 2.5A regulated: *585 Hz*
CustomLites Luminus SST-90 3 mode direct-drive: *485 Hz*

ZebraLight H50: *NO PWM*


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