Just got my Fenix L2D Q5

jnj1033

Newly Enlightened
Joined
May 25, 2006
Messages
197
Location
Los Angeles
My Liteflux LF2 sings a little when I have it set to the higher modes. Also, my MagLED 2D squeals on startup. Someone posted a while back about picking up radio interference from a MagLED.

I have a P2D CE that I bought a year ago, and I've never heard any sound from it.

J
 

kts

Enlightened
Joined
Dec 5, 2007
Messages
359
My L2D CE P4 is silent..I had a L2T V2.0 that had the whining syndrome, it used a rebel 80, it didnt whine if you took of the tailcap, it also flickered slightly in high mode, so I guess it was a faulty tailcap, I got a P2D Q5 instead, total silent.

2 of my LODs whines a little, the LUX3 and the CREE Q4..my LOD CREE P4 is silent, the LODs is more buzzing than whining, and theyre all silent on high, so the sound is coming from the PWM.
 

HKJ

Flashaholic
Joined
Mar 26, 2008
Messages
9,715
Location
Copenhagen, Denmark
Oh wow, HKJ! I wasn't expecting anything as analytical as that... :thanks: !


I did it because I was curious, we always says that the reason for sound from the light is the switcher, but a modern switcher always uses a frequency well above the audible range and as can be seen, Fenix does that as well. It is some sort of oscillation in the regulation that can produce sounds, not the actual switcher frequency.

The two flashlights uses two different heads, I tried to swap the heads, the 800 hz is following one head, i.e. it must be some components (tolerances) in that head that does it.

When I listen to the head, it can not hear any noise, i.e. the inductor is fully potted.

I also tried using a photo sensor on the light, the 800 hz is also present in the light.
 

HKJ

Flashaholic
Joined
Mar 26, 2008
Messages
9,715
Location
Copenhagen, Denmark
How exactly do you measure the data with the flashlights?

A PC Scope from PicoTech and a current clamp, I also have some multimeters (Fluke and others), but for current measurement at high currents, the current clamp wins.
The reason for that can be seen in the https://www.candlepowerforums.com/threads/199298 thread, where I had to adjust my measurements, because I started with a multimeter. :oops:

For measuring the frequency in the light I used a led connected to the scope, it works at 800 hz, but I would like something with a bit more bandwidth. Maybe I will try adding a opAmp to the led.
 
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