L2D Q5 whine / noise

LEDBE
P

peacetoall

Guest
Hello,

Newbie to the forum. Purchased a L2D Q5 but it had a perceptible high pitched whine especially in the turbo and strobe mode. Ended up returning it but was informed that this is due to the LED engine and it was normal. Is this a common occurence and what do you'all think about it.

Still, the Q5 is a phenomenal bargain.

Thanks and peace.
 
I have the Fenix P2D recently purchased and find that in turbo and strobe mode it did cause a high pitched whine, I recall having this issue on my Fenix T1, with use I have found the whine to disappear. My T1 doesn't have the whine anymore, even with fresh batteries. My P2D still has the whine in turbo mode.
 
There are plenty of threads about this issue.
It seems to be normal and mine suffers from it also.
 
You're hearing the oscillator oscillating. :)

Generally this happens when an inductor on the regulator board couples some of it's energy to a nearby piece of ferrous metal, causing it to vibrate at the frequency th at it's operating at. Sometimes the coil itself vibrates a little bit, causing the sound.

If it really concerns you, it might be possible to dampen the sound a little bit by potting the area with some Ceramique or similar heatsink goo. Regardless of whether you can hear it or not, it's perfectly normal. It's the same reason why many tv sets havce a high-pitched (15.734khz) whine.
 
I just ordered a L2D-CE combo special that comes with an E01. It doesn't have the Q5 emitter.

Does this older model have the same problem?
 
JWP_EE said:
I just ordered a L2D-CE combo special that comes with an E01. It doesn't have the Q5 emitter.

Does this older model have the same problem?
Click to expand...
It is mainly the newer models with polarity protection that it can be heard.
Mine is a Q5 without polarity protection and I can hear a very quiet hiss so the P4 model may have the problem too I can't say, but it is not noticeable with mine unless its right against you're ear in a quiet environment.
 
PhotonWrangler said:
You're hearing the oscillator oscillating. :)

Generally this happens when an inductor on the regulator board couples some of it's energy to a nearby piece of ferrous metal, causing it to vibrate at the frequency th at it's operating at. Sometimes the coil itself vibrates a little bit, causing the sound.

If it really concerns you, it might be possible to dampen the sound a little bit by potting the area with some Ceramique or similar heatsink goo. Regardless of whether you can hear it or not, it's perfectly normal. It's the same reason why many tv sets havce a high-pitched (15.734khz) whine.
Click to expand...

Thank you for a comprehensive explanation. I had a L2D Cree but it did not have the noise issue. A few folks said that this was seen more with the Q5 L2D. I am considering purchasing another flashlight with similar specs price as the L2D Q5 but I am flexible in that regard. I find the whining noise somewhat bothersome and would rather have something that tends not to do that.
Eventhough the Nitecore D10 and the Fenix T20 both have less output, overall they are still attractive flashlights. I want buy just one. Any suggestions?

Peace.
 
Nitecore D10 is at par with L1D Q5; in fact its a bit higher with its smart PD system and continuous brightness adjustment. T20 is lower than L1D Q5 in lumens aspect but its specialty is it being a thrower compared to L1 or L2.
 
You are hearing the coil vibrate at the frequency that the pulse width modulator is running at. It comes from magnetostriction; the induced pulse current through the winding pushing them back and forth from the core. The louder it is just means the windings are a little loose from the core and have some room to vibrate. It is not a bad thing, it is not defective. The pulse width modulator is running in the audio frequency range so you can here it. I have various units that I hear it on. Some more than others. The pulse width modulator creates its own oscillation frequency based on a resistor and capacitor in the input circuit and the RC time constant it creates, but there is no actual "oscillator" individual component. The PWM will not make any noise from the frequency as it is a solid state device.

If there was an actual oscilator with a piezo electric quartz crystal, it would be running at much higher frequency and divided down, it would not be running in the audio frequency range. It would run in the high hundred kilohertz or megahertz range and you certainly would not hear it. Such a component simply is not necessary with the pulse width modulator that can be made to modulate at a wide range of frequencies based on a very small resistor and capacitor. This is what I have seen in the pills I have looked at and the schematic circuits I have seen published for some of them on the web.
 
I might be the only one, but i enjoy the humming of the L2D. Reminds me
of a mini lightsaber. Even the 2aa body tube is kinda light saber-ish in its design.

a coworker of mine asked why it was making noise when i lent it to him. i didnt want to try to explain, nor knew the real reason, so i just told him "because of its high power..you know like the buzz on high
power transformers on electrical lines" :whistle: he said oh ok.



if the windings are a bit loose, can you rewind with new magnet wire?
will fine tuning the lenght/guage of wire, give you a different current output
to the led?

I've hand rewound rc motors with thicker guage magnet wire to draw more current/torque and thinner guage+more turns to provide higher rpm, just wondering if a similar concept applies here.
 
Last edited:
abvidledUK said:
Does this whine attract / repel dogs, flying insects ?
Click to expand...


Short answer is no. Its not in the ultrasonic frequency range that repels some critters, since you can hear it. Its down around 10KHz or maybe less. It only repels flashoholics.
 
Glowman said:
Nitecore D10 is at par with L1D Q5; in fact its a bit higher with its smart PD system and continuous brightness adjustment. T20 is lower than L1D Q5 in lumens aspect but its specialty is it being a thrower compared to L1 or L2.
Click to expand...



Just remember, crack kills!

My L2D-CE has some whine on max but you have to hold it to your ear to hear it. My LOD has even less and the rest of my lights are silent. No harm in a little wine.............................:)
 
You don't want to try and rewind a 25 cent piece part made in China already soldered down to the board. You will probably ruin it. Its set to a certain value inductance for the buck driver's PWM to work. You aren't going to improve it. If you want the noise to go away potting it with RTV or an epoxy might help.

For all you guys who love to experiment the real question is for the ones you don't hear, is it because its at an ultrasonic frequency, or simply quiet. If you turn your flashlight on and hold it near your pet dog or cat where they can hear it (not shining the light on them of course), and its driving them crazy and you can't hear it, its humming at an ultrasonic frequency. If the dog or cat looks at you like you are stupid, they are probably right, and also your flashlight is not humming at an ultrasonic frequency. :nana:
 
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