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Using the host driver?

Toke

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I have just dismantled* my Fenix PD30, the pill? appear to be solid with holes drilled for wires, so fitting a driver in will not be easy.

I am thinking of making a cylinder 14,2mm long and 18,8mm wide with a hole for a 9mm module, or front and business of a 12mm module. It would replace the reflector and glass.

My tailcap measurements show 0,76A at high setting.
It looks to me like it would be a perfect fit for a 140 diode.

Does anyone know what the driver is doing?
Like anything nasty as transforming the 6V 0.76A down to too many amps.

(Yes I could unsolder the LED and find out myself, but I see no reason to take any risk if someone here know about it.)

*Nondestructively so far.


ETA:
The Cree XP-G R4 emitter:
130-347,5 lumen
350-1000 mA
3-4V
1.05W

It looks really good to me, and as if the low power modes of the light is achieved by pulsing the light.
 
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comradmax

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can you tell if it's PWM or Buck/Boost? I am trying to figure out why there arent more people using flashlight drivers for lasers. so far i've read a few posts here and there, looks like this question is starting to get asked... i dont know if this has been covered in the past, and the conclusion was that lasers need special drivers, like the 2 popular ones used by most people currently.

here is what i think i've understood with my very basic understanding of electronics, and i can be totally wrong about all of this:

1) PWM is bad for LD, but OK for LED - LD wants buck/boost circuits.
2) it may be that LED drivers do not have to pay too much attention to small current spikes, whereas LD will burnout from the same driver.

if it's #2, then can one solder the same capacitor as on the popular LD modules on the output and smooth out the spikes? reading some posts it sounds like people have tried this, but i still cant find any definitive answer with explanations why it would or would not work...
 

Toke

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can you tell if it's PWM or Buck/Boost?
Well, I do have a Fluke-scope on the shelf here, that could tell me if there is pulse with modulation.

And yes, I guess it could be either 1 or 2 as well, and that a capacitator and maybe small resistor across the diode should solve 2.

It could also be 3)
That the currents rarely match.

I just thought the answer were well known, since the use of flashlights for hosts is not a new thing.
 

Toke

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Ok, the voltages across the LED are 2,728V, 2,928V, 3,043V, and 3,269V, with nothing measurable on HZ.
So no PWM on Fenix PD30

(Yes those US types got, and . swapped in numbers, too bad.)
 

chipdouglas

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can you tell if it's PWM or Buck/Boost? I am trying to figure out why there arent more people using flashlight drivers for lasers.
.


from what i have read is that LED drivers are not as stable as the drivers we use. LD's are much more sensitive. not to say all LED drivers are stable, but if you are a novice or non technical is it worth blowing an LD? so it is more of a preventative measure as apposed to a "no you cant do it'

michael.
 

Toke

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That could be it.
I just checked for HZ across the tail cap, none except for 14HZ on strobe.
So it looks like a linear driver to me.
One with a fixed current setting, and maybe not as stable as a proper laser driver.

One practical problem I see is the connection of the LD, I want it soldered which means I would have to drill out the pill anyway. The wires from the driver goes through separate holes and would twist up a lot when screwing it together.

Guess I should look for a cheaper host.
 

Morgan

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can you tell if it's PWM or Buck/Boost? I am trying to figure out why there arent more people using flashlight drivers for lasers. so far i've read a few posts here and there, looks like this question is starting to get asked... i dont know if this has been covered in the past, and the conclusion was that lasers need special drivers, like the 2 popular ones used by most people currently.

here is what i think i've understood with my very basic understanding of electronics, and i can be totally wrong about all of this:

1) PWM is bad for LD, but OK for LED - LD wants buck/boost circuits.
2) it may be that LED drivers do not have to pay too much attention to small current spikes, whereas LD will burnout from the same driver.

if it's #2, then can one solder the same capacitor as on the popular LD modules on the output and smooth out the spikes? reading some posts it sounds like people have tried this, but i still cant find any definitive answer with explanations why it would or would not work...

I don't think this true and is a little generalised. LDs in most drives that we use are pulsed in their normal environment. It's more the stability that is crucial and it's the filtering capacitors that are missing from some LED drivers.

M
:)
 

Toke

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Now I read it, I am reminded of data sheets saying something about duty cycles and max pulse width at high powers.
That reduces the problems to convenience of fixed current setting and stability, the later might be handled by a large capacitor across the diode.

If I test this it will be with a cheap host and diode.
(Both are in the mail. :))
 

comradmax

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ah, so PWM if not bad per se, it's that the widely available PWM drivers dont have the most stable output. and #3, of course, now that you said it, makes perfect sense:)
 

BShanahan14rulz

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Many PWM "drivers" are simply a gate that opens and closes very quickly to allow the LED to be directly driven from the battery.

What driver is in the fenix, toke?
 

Toke

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Many PWM "drivers" are simply a gate that opens and closes very quickly to allow the LED to be directly driven from the battery.
There is supposed to be an capacitor to even out the voltage at rated.

What driver is in the fenix, toke?
The lack of Hz measurements on both the diode and the tailcap make me guess linear.
 

Toke

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I am not sure if PWM is particularly "Cheap".
If part of your driver ensure the correct max current it would be one way to dim the light, it works fine with florescent tubes and diodes should withstand it even better.
(I can't imagine anybody trying PWM with more than max current)
It is just that it would be noticeable when measuring voltage across the LED, at least with a Flukescope.

Using a switch mode driver would pulse the current from the battery and use a cap to smooth it on the LED end. That would be noticeable when measuring the tail cap current.
(I guess the excess energy from the voltage drop is dumped as internal resistance in the battery)

As I could not measure any pulsing at either LED or tail cap, so I go for linear driver.
 




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