RedForest UK
Flashlight Enthusiast
- Joined
- Nov 28, 2009
- Messages
- 1,365
I think that the confusion comes from a change in description of the circuits. I have actually asked someone at Niwalker about the regulation on the BK-FA02. Originally they had described both as constant current, as I believe that both use buck circuits which can provide constant current to any LED with a Vf lower than the input. However with the carrier in 2s2p arrangement the voltage input drops a little below Vf of the MT-G2 at higher levels, this is something that they may not have entirely anticipated in earlier stages of the design process as without the voltage drop caused by the circuit itself I don't think it would be much of an issue at the current levels seen.
Having sent the pre-production samples to selfbuilt for testing and seen the results they had the choice to either update the circuit or change the description to remain honest. They decided that the slow natural stepdown was not a problem for them, as it provided a natural form of thermal protection meaning they didn't need to implement a programmed stepdown after a few minutes. It is also very efficient with hardly any driver loss as there is minimal to no voltage conversion, and so maximises the runtime overall. Also, in actual use it is not noticable.
When the graph is visible in it's entirety and a long period is condensed into a line which you can scan in moments then changes in output seem fast and like they would be noticable. However, if you were to plot the same graph on a larger scale, even at a size that represents 5 minutes but can be viewed in a second, then even the sharpest changes would seem much lower.
In real time they are completely unnoticable. I actually recommend that you do this if you have any doubts. Try plotting a period of the graph which you feel would be noticable at a much larger scale and you will see the incline of output change level off dramatically
Anyway, with that in mind they changed the product descriptions to best represent the circuits' actual behaviours. I believe that they are being compeletely honest, but can see where the confusion has arisen.
By the way, having asked Niwalker, they have let me know that the main improvement to the production versions was to use a copper core PCB for the LED, which could account for the increase in max output. I am looking forward to reading more about the production versions and any further updates that have been made.
Having sent the pre-production samples to selfbuilt for testing and seen the results they had the choice to either update the circuit or change the description to remain honest. They decided that the slow natural stepdown was not a problem for them, as it provided a natural form of thermal protection meaning they didn't need to implement a programmed stepdown after a few minutes. It is also very efficient with hardly any driver loss as there is minimal to no voltage conversion, and so maximises the runtime overall. Also, in actual use it is not noticable.
When the graph is visible in it's entirety and a long period is condensed into a line which you can scan in moments then changes in output seem fast and like they would be noticable. However, if you were to plot the same graph on a larger scale, even at a size that represents 5 minutes but can be viewed in a second, then even the sharpest changes would seem much lower.
In real time they are completely unnoticable. I actually recommend that you do this if you have any doubts. Try plotting a period of the graph which you feel would be noticable at a much larger scale and you will see the incline of output change level off dramatically
Anyway, with that in mind they changed the product descriptions to best represent the circuits' actual behaviours. I believe that they are being compeletely honest, but can see where the confusion has arisen.
By the way, having asked Niwalker, they have let me know that the main improvement to the production versions was to use a copper core PCB for the LED, which could account for the increase in max output. I am looking forward to reading more about the production versions and any further updates that have been made.
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