for a color mix I want to play with, I’d like to use something like this with one “lime” and two “amber” emitters, specifics below.
(they’ll have Noctigons with the same electrical setup soon) — which can be set up either as three separate emitters, or three in series
I don’t have any particular host for this idea yet, but I’d expect it would be a single li-ion
Floody, used mostly indoors, without optics or with one of these:
Driver and wiring is the puzzle — how can I do this?
350mA to each emitter would be fine; no more than 700 mA to each of them at most (don’t need more)
I’d like to combine three emitters all at the same time:
one of these new “lime” emitters
Minimum Forward Voltage 2.6 Vf
Typical Forward Voltage 2.75 Vf
Maximum Forward Voltage 3 Vf
and two of these phosphor-amber:
Minimum Forward Voltage 2.55 Vf
Typical Forward Voltage 3.05 Vf
Maximum Forward Voltage 3.51 Vf
Can I run these in series, giving each of them no less than 2.55 V, and no more than 3 V?
Or, should they be run in parallel, like a multipart RGB, a pair of wires to each emitter?
And in either case — what am I looking for in a driver?
An LED is driven using current.
You should wire the LEDs in series so that they all get the same current. If you wire them in parallel one of the LED (the one with the smaller Vf) will get all the current.
In series they’ll all get the same current. Don’t worry about the Vf. Just get a driver than can supply 350mA or 700mA.
Something like this
Just check that your input voltage is between 6 and 8.4V and you’re good to go!
hm, I want to use a single li-ion
(I don’t have any multiple-cell lights and prefer not to get into that.)
I’d like to host it in something like the DQG 26650 Triple (one cell, three emitters).
(I have no idea what the driver in that is, so I didn’t risk just swapping emitters)
What you can do is use a 3 channel driver (but the simple way where the 3 channels are all controlled by the same PWM output, so they arnt individually addressable (cant be on one at a time) but they are electrically isolated from each other and wont have issues since the 2 colors are different vf’s like if you just wired them all together. (What Lagman is saying about wiring them in series would work but you’ll need a boost driver to run that string from a single li-ion).
I dont have anything already made but could design something pretty easily for you, go ahead and PM me with the exact details, I’ll probably need your host (or atlease the host’s factory driver) and a couple of weeks time (oshpark is back to taking a couple weeks) but I can do exactly what you’re after. Same principal as the 3 channel SRK driver that we have, it will power 3 emitters all at the same level but they’re completely isolated so you can use different emitters without killing one or two like if you hooked different emitters in parallel with one another for the reason lagman explains above’
+1 for DrJones’ driver, his board is already setup for 1 or 2 7135’s per channel. And his FW is awesome, I just got my first of his proprietary FW’s (I use luxdrv quite a bit). Do note his driver will require an e-switch light, no way around that.
OK. Bear with me here, I’m educating myself. Feel free to ignore, of course.
So I’m ruling out the simplest way to “wire the LEDs in series” — the simple circuit like
+LED~~+LED~~+LED——
Idriver__I
and we’re talking about, um, can someone point me to circuit drawings showing how the sophisticated multi-emitter drivers work?
Not asking for any proprietary secrets, just some notion of how a driver hooks up to three different emitters, and how it gets to the emitters. I understand this gets into programming — pointer welcome, I’m sure it’s explained somewhere, I never ventured into that.
(Meanwhile I’m going to look up “e-switch” lights)
An e-switch is a electronic switch (as opposed to a standard clicky switch). An e-switch sends a small signal (all the ones I use simply send a few mV ground signal to the switch input pin and the MCU monitors for these ground signals and changes modes/turns on and off by interpreting the timing of these signals.
A clicky switch driver changes modes based off the power cycle (power is either applied or cut) with an e-switch power is always flowing into the driver (just a few uA when light is off) so the clicks can be timed, the MCU can’t time power interrupts since it dies instantly when the power is cut it can’t run its clock or do other functions.
I will make a few drawings real fast.
Does this help?
What you see here is a series setup (top left), a parallel setup (top right) and a independent Ch on the bottom like you need (but all 3 channels are still controlled by the same PWM output so the LED’s arnt individually addressable like if they had their own PWM signals from the MCU). The advantage is that one LED wont suck up all the power like is possible in a parallel setup. Parallel is great when you’re using multiple’s of the same exact emitter (but even then you can still have problems because of the natural variation from one emitter to the next), this way even tho the regulators are all connected together their output’s are isolated from one another so one cant run away and kill its self.
