It will be slight. 40% is about 1.5dB which you can discern only using side by side comparison like what I've been doing. But it is quantifiable and measurable.
Nitecore EX10 Circuit Discussion
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It will be slight. 40% is about 1.5dB which you can discern only using side by side comparison like what I've been doing. But it is quantifiable and measurable.
koala
Flashlight Enthusiast
If your Cree emitter has abnormally high vf, then swapping one with a low vf will also increase the current. That's what happen to me when I rig the circuit to an old Q2J test LED, the current dropped indicating that the Cree that I have has a lower vf than the Q2J.
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Update to my last mod.
I took off the 0.1 ohm resistor I had put in several days ago and replaced it with two 0.15 ohms in parallel for a current in excess of an amp to the LED on high. Now the output measures 75% to 80% brighter than stock but drops off slowly as the die heats up. It is *noticeably* brighter and is getting close to the output of the Arc6 on high using RCR123's. Now this light is impressive for its size. It gets hot very quick and since there is zero thermal management such as that in the Arc6, it can get dangerously hot. But damn, it's fun during the short five or so minutes I'm able to hold it in my hands
I took off the 0.1 ohm resistor I had put in several days ago and replaced it with two 0.15 ohms in parallel for a current in excess of an amp to the LED on high. Now the output measures 75% to 80% brighter than stock but drops off slowly as the die heats up. It is *noticeably* brighter and is getting close to the output of the Arc6 on high using RCR123's. Now this light is impressive for its size. It gets hot very quick and since there is zero thermal management such as that in the Arc6, it can get dangerously hot. But damn, it's fun during the short five or so minutes I'm able to hold it in my hands
Question came up in this thread -
NiteCore EX10 Comparison Review
How does the emitter Vf affect brightness in the EX10?
The circuit is a booster - but what else? - is it
constant current,
constant voltage
or something else?
Thanks for any help.
NiteCore EX10 Comparison Review
How does the emitter Vf affect brightness in the EX10?
The circuit is a booster - but what else? - is it
constant current,
constant voltage
or something else?
Thanks for any help.
Bullzeyebill
Flashaholic
Looks like constant current with PWM dimming.
Bill
Bill
According to koalas findings it is constant voltage
Thank you for that -
I also just got an e-mail from 4sevens - the EX10 is a voltage regulated circuit
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Bullzeyebill
Flashaholic
Not sure about it being voltage regulated. Everything that CM has done to modify the bias indicates, it seems, that it is a current regulated design.
Bill
It is entirely possible that the circuit is voltage regulated. However, voltage regulation is not the preferred way to bias LED's in volume production because of the wide variation in Vf. You will either have to tweak each one OR accept the wide variation in LED forward voltages. I don't think they tweak each one, so accepting the wide variation in Vf means that they either have to design for the worst case Vf to meet their output claims but that means some LED's will be driven pretty hard (possibly out of spec). The ones driven hard is susceptible to thermal runaway.
I have used voltaqe regulation to bias a LED (only once since the Vf-If transfer characteristic is highly non-linear) and I can't imagine having to adjust each unit in production to make sure it is within the operating envelope specified by the manufacturer.
However, the key thing to note is that regardless of the the type of regulation (constant voltage or current), evidence shows it is a boost circuit. This is emminently more useful knowledge than constant voltage or constant current since it defines some of the operating limitations of the circuit for us who wish to modify or use this with other input voltages/LED drive currents.
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koala
Flashlight Enthusiast
According to koalas findings it is constant voltage
Huh, Where? Did you derive that from my data? Care to explain? Thanks everyone a lot of interesting stuff to learn here.
According to koalas findings it is constant voltage
Where is that stated ?
I was referring to this post.
I overlooked that drop of voltage, but the difference in current clearly indicates that it is not constant current but drop of voltage also indicates that it is not constant voltage? :huh:
mdocod
Flashaholic
CM,
Thank you for running those tests, I had been under the impression that these types of lights were boost/buck, these tests prove that very much wrong and I'm beginning to think that this probably holds true in many other lights that are rated "0.9-4.2V" ... I'll be taking this into consideration for my compatibility chart for LED lights
Eric
Thank you for running those tests, I had been under the impression that these types of lights were boost/buck, these tests prove that very much wrong and I'm beginning to think that this probably holds true in many other lights that are rated "0.9-4.2V" ... I'll be taking this into consideration for my compatibility chart for LED lights
Eric
You can't draw conclusions about whether the circuit is constant current or constant voltage based on the graph. The only conclusion you can make is whether it is a buck or boost converter.
CM,
Thank you for running those tests, I had been under the impression that these types of lights were boost/buck, these tests prove that very much wrong and I'm beginning to think that this probably holds true in many other lights that are rated "0.9-4.2V" ... I'll be taking this into consideration for my compatibility chart for LED lights
Eric
You're welcome. CPF is such a great forum but there are so many half-truths and not-true's that are being propagated that it's increasingly difficult to get through the noise. I'm hoping that more people are encouraged to perform objective testing and posting their results.
If it was constant current driver then current to the led would be the same with both leds that koala tried. And because it wasn't (385mA vs 605mA is pretty big difference) it is safe to say that it is not constant current driver
koala
Flashlight Enthusiast
:naughty::naughty::naughty:
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If it was constant current driver then current to the led would be the same with both leds that koala tried. And because it wasn't (385mA vs 605mA is pretty big difference) it is safe to say that it is not constant current driver
Look at koala's schematic above and tell me what the 0.15 ohm resistor is for
And for you, koala,
:thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:
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