Fallingwater
Flashlight Enthusiast
Apologies if this is a silly question - I haven't tinkered with LEDs for ages and with coloured LEDs for even longer, so I've forgotten a lot of what I knew.
I'm making a lighting system for my bicycle. I'd like to use a single red Cree Q5 in the rear and a white one in front. (Why such old LEDs instead of newer ones? Because I have them sitting around.) The power source for both is a single 18650.
Driving the front one isn't going to be a problem, as I have plenty of surplus drivers from back when I used to tinker with flashlights, but what do I use for the rear one? The lower Vf seems a bit of a problem - 7135 drivers or simple resistors would become tremendously inefficient, and though I have some switching drivers they're meant for white LEDs and I'm not sure how they'd behave with a red one.
Edit: I tried one of the switching drivers. It draws the same current for both LEDs and drives them at the same level, so it's obviously dissipating the extra voltage and being inefficient.
I'm making a lighting system for my bicycle. I'd like to use a single red Cree Q5 in the rear and a white one in front. (Why such old LEDs instead of newer ones? Because I have them sitting around.) The power source for both is a single 18650.
Driving the front one isn't going to be a problem, as I have plenty of surplus drivers from back when I used to tinker with flashlights, but what do I use for the rear one? The lower Vf seems a bit of a problem - 7135 drivers or simple resistors would become tremendously inefficient, and though I have some switching drivers they're meant for white LEDs and I'm not sure how they'd behave with a red one.
Edit: I tried one of the switching drivers. It draws the same current for both LEDs and drives them at the same level, so it's obviously dissipating the extra voltage and being inefficient.
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