2 LED driver boards, each in series with another LED, in parallel
@TorchBoy
you´re right - i thoungt about the 3x 3xAMC7135 Boards. (multi level)
My Plan is to use 4 of them to drive a 4x XR-E light - with 2x 18650 in a row.
OK. Should work well with just two of those boards, and your switch should only have to handle ~0.4mA. How's that? :twothumbs
if i use a normal diode (or multible), want it kill the effectiveness ?
It would, because you'd be getting no return (light output) for the volts dropped. But using an LED instead
won't kill the effectiveness because you'll drop the necessary volts
and you'll get the extra light you want. The arrangement will also save some voltage, because the AMC7135 has at least 0.12V dropout, so it'll be slightly better than using two boards in series as the battery goes flat. It also means that just one board will be doing the mode control for the two LEDs in series, which might be a good thing, depending on how well they worked together (
if they worked together).
to use a xr-e to drop the voltage sounds interesting, but i think i didn´t understand the wiring you ment ...
can you exlain how to use the led to drop the voltage ?
Simply insert it between the battery and the board, where you would put a switch if you wanted to completely turn off the current, so that all the current flowing around the circuit goes through it. It doesn't matter whether you attach it to the positive side or the negative side of the board.
multiemitter always in series,
drive it with a step-up driver, when You want to power them with two 18650s.
It's not essential at all. As long as you're not going to get in to a current-hogging situation by having one driver feeding multiple LEDs in parallel, it more depends on what driver you have available (for what price), and what features you want in a driver. In this case the multimode board is quite attractive. But feel free to suggest drivers that you think would be suitable. They may be more suitable than my suggestion.
That way all the led see the same current, switching is easier, less to goo
, ...
As I said, the difference in current between the two LEDs will be 0.2mA, and in a 4 LED light, if one board unexpectedly dies you will still have the other, still running two LEDs.
One other advantage of doing it this way is that to turn on the light you only need to switch the set pins of the two boards, which means you're switching a total of 0.4mA, which means it's basically acting like a linearly regulating relay - very clever. You'd need a double pole switch if you wanted to keep them separate, but my first thought is that wouldn't be necessary, just take the positive feed from one of the uphill LEDs only.
Happy new year.
