Fireflies PL47G2 Discussion Thread

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nuemtol
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Joined: 04/23/2019 - 01:26
Posts: 107
Location: USA

Hi, is the ff-light.com website down for everyone?

https://www.isitdownrightnow.com/ff-light.com.html

thefreeman
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Joined: 01/06/2020 - 09:56
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Location: Europe

hi,
I disassembled it to see what package the aux leds are, as guessed by Firelight2 they’re 603 (1608 metric) leds, but I measured the voltage and resistance and it’s a bit strange, voltage across a led is 2.56V, and across its series resistor is 0.96V (10kΩ), firstly that doesn’t add up to the voltage of the cell (4V at the time), but maybe there is some voltage drop from the controller or something.

Secondly the voltage across the leds is a bit high, the current per led is 0.96/10000 so 96µA (which approximately add up to the current drain directly on the cell), the cyan leds 603 that I found should have a lower voltage at such low current (although not that much, 2.3~2.4V)

But if I want to replace with amber leds like this one with about 1.6~1.7V fV at very low current, the resistors should be more about 20k for 96µA (3.5-1.7/0.000096=18750)… , with the original 10K it’ll be about 180µA per led which will drain the cell 2 times faster.

the cyan leds linked are like ~30mcd/mA though, while the amber is ~4.5mcd/mA, huge difference, but the aux leds are originally way too bright for my taste anyway.

Any mistakes here ?

I guess I should either change the resistors, or simply put half as much leds to keep the drain similar (about 1.6mA total at 4V cell), I’m probably going to do the latter, less work and the resistors are 402(1005), not sure I have the soldering skills.

Changing the button led would be nice too, but the retaining ring seems difficult to remove, at least without damaging the switch cap, press fitted rings are annoying…

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