Flashlight concept #1 - Multi-emitter light

You do the math wrong, we already have a thick copper MCPCB which reduced the temperature difference between a copper or aluminum head
Ask any here in forums why we don’t want to use aluminum MCPCBs even if they are DTP, the heat conduction is absolutely critical to keep the LED temperature low

Nobody wants to store the heat near the LED, the cooler it runs the better its photon conversion is, so people asked manufactures for thicker shelves on the BLF lights to move the heat faster away and give more heat buffer

I have done several thermal imaging videos of aluminum heads, the heat from the hottest to the coldest spot is minimal as the conduction of heat is already very good on flashlights with a thick shelf and thick walls

Your 0.2% on DD drivers is also wrong math
look on a Samsung 30Q battery for example and look how much 40mV voltage difference between a hot and cold LED result in current change
I did here the graphs between 5 and 7A and on average I would say about 40mV difference

so your 0.2% I don’t know how you calculate that number results in my calculation for 40% current change without any resistance added
so lets take bypassed springs and switch with 50mOhms and driver and LED leads also 50mOhms
40% change on 16mOhm of the 30Q cells, now lets do the math with all resistances I get 5.5% less current on DD light just by 20°C lower LED temperature

I mean a 100% copper light with copper tube, most people touch a hot rod light only on the tube, the better it conducts heat the more the human heat sink plays a role

So, a press-fitted copper pill and/or soldered MCPCB could probably be more efficient in terms of weight, thermal conductivity and dissipation as well as being more cost-effective?

Using a full copper body would definitely increase both weight and cost dramatically. I was hoping to match the best of three worlds (Titanium for a sturdy bezel, Copper for best thermal transfer, Aluminum for best and fastest heat spreading/dissipation alongside the battery tube with the benefit of less weight).

The idea about tint mixing originates from Sofirn's IF25 and the LT1 lantern. Basically, I would like to enable every customer to choose his/her favorite tint between warmwhite and neutralwhite. We could also go up to 5.700K 90CRI - no big deal. There might be certain situations when people like using neutralwhite (outdoor in summer) but also want to change to warmwhite (outdoor in winter with highly reflective snow/iced surfaces or when inside) with the same flashlight. If tint-mix is not an option we could still mix LH351D 2.700K 90CRI with 5.700K 90CRI to get rid of any greenish tintshift and drive the mixed tint below the BBL resulting in a rosy tint pattern somewhere around 4.000K. Just thinking...

Why is 2.700K so much less efficient? Because most (all?) warmwhite emitters seem to have less efficiency than coldwhite emitters. I do not have accurate numbers for LH351D 2.700K 90CRI but I quickly translated the reduced output by the expected loss in efficiency. We may get a bit more output here but I wanted to keep the numbers conservatively calculated.

If multi-footprint MCPCBs are feasible, how about replacing the inner XP-E2 deep red by an Osram White Flat KW CSLNM1.TG 1mm²? This would give us a flashlight with both flood (6x LH351D) and throw (1x Osram White Flat 1mm²).

Looking on Digikey as a source for LH351Ds
I get 2700K CRI90 310 and 330LM binnings
for 5000K CRI90 390-410 binnings

so 4000lm for 5K
and 3200lm for 2.7K

Looking on Digikey as a source for LH351Ds
I get 2700K CRI90 310 and 330LM binnings
for 5000K CRI90 390-410 binnings

so 4000lm for 5K
and 3200lm for 2.7K

also why not simply compensate the lumens in the firmware to have on any color 3200lm just do the 5000K only on 80% max current?

Just to get it right: Do you mean a balanced output, i.e. the flashlight will always have let's say 3200 lumens output regardless of the tint's CCT?

yes

you could then also make in the firmware an option to blast out Turbo with all LEDs and max current at about 4000K

Okay, I got you. :-) Good idea. Sofirn did not balance the output on the IF25 (yet). Effectively, not only in perception but also in actual numbers it is brighter on coldwhite than on warmwhite. They also did not implement the fancy feature of using all 4 LEDs on Turbo (yet). However, your ideas definitely belong to the wish list of the UI a perfect flashlight should have.

A revised draft concept...

Ehm...IN!!!!

Hmmm… Tint ramp is not a huge thing for me, but then again, I’ve not used a light with tint ramp.

I like the idea of a separate red in the center. Sometimes you need a more gentle and nighttime friendly light. Then again, dropping what I assume is an Osram thrower in the middle defintely adds flexibility. The unicorn flood/throw combination light.

Size — I’m torn on this one. As a pocket light, even the 21700 might be a bit big for my tastes, let alone a 7 LED head. As a holster / shelf light, I like the feel of a 26650 tube, which might be a better size match for a 7 LED head. (reference - I have most recently used an FW3 and EDC18 as my pocket lights, and they are IMHO, on the edge of being to big for pocket EDC)

I was wondering about this the other day, and since I saw this, I figured I would ask. Is there any potential advantage to using the red LED in the tint mix? Most phosphor-based white LEDs tend to lack red, right?

ETA: Or is that already the plan?

I don't know if using the red emitter in combination with the surrounding white emitters would result in a nice beam pattern. I would rather expect it to look weird. So, the red / deep red emitter is more likely to work separately as auxiliary illumination in lowlight scenarios (e.g. camping, preserving one's night vision, no attraction of insects, nightstand light, ...). Using the Osram White Flat 1mm² instead could be interesting to put out more throw as a centered hotspot in combination to the floody LH351D beam.

This looks like a great concept, I like it. I’d be more of a 4-LED 18650 kind of guy for EDC, but this seems like a good camping trip flashlight that can also serve as a lantern. 5700K while hiking for visibility, mixed tint while cooking food and 2700K when relaxing and reading a book. Just throw on a silicone diffuser and you’ve got yourself a lantern. Maybe a folding hook in the rear to be able to hang it in the tent or from a tree, with a magnet in the cap to keep the hook folded and still being able to stick it to metal surfaces.

I’ve been waiting for my IF25 from Aliexpress since 11/11, but I’m not sure when it will arrive, or how good it will be with the 70CRI 6500K SST-20s. Also waiting for my BLF LT1, but a flashlight like this could replace them both for my use.

So, I revised my original idea and tried to set up something new, something easy to operate...

(please excuse this rather simple design draft....just for illustration...)

Specs:

Output: approx. 4.200lm white light with a mixed tint of 4.500K 90CRI and approx. 400lm deep red light (660nm), emitters to be driven efficiently - not pushed to their limits

Host: Proprietary, mid section maybe based upon Sofirn SD05 or IF25A, front section (head) new design with wider head diameter (40-42mm), tailcap + switch Sofirn SP70

Optic: LEDiL TAMPA NIS83-MX-7-W (wide beam, 35°, 38mm diameter)

Bezel: Stainless steel bezel

Emitter: 3x LH351D 4.000K 90CRI, 3x LH351D 5.000K 90CRI, 1x SST20-DR (660nm)

Driver: fully regulated boost driver (wishful thinking)

Power: 1x 21700 flat top

UI: magnetic rotation ring controls stepless brightness only (moonlight to turbo), tail switch controls modes (tap for mode selection between white and red light, fully press for ON/OFF)

I like this new idea :wink: :+1:
Seems a very well thought flashlight!
One question, though: the tailswitch would be a e-switch or a foward clicky switch?

I like it.

I like this, too. Nice design.

How about 9 LEDs? or have both a 7 and 9 LED variant.

Edit: 9 months ago I said 4 LEDs :open_mouth:

I like the thrower version.

Am I a minority here or what, but why would someone want a flashlight that is anything <5,000K. I know that a lower number K LED light will yield a higher CRI, but this is a flashlight after all and not photography lighting. If someone wants higher CRI then he/she might as well go back to using incandescent light bulbs. Newbie here, so please educate me.

I have my fire suit on, so go ahead: fire away.

Hi tammap!

It all comes to a matter of personal preference. For example, I use my warm white FW3A a lot at night when my eyes are alredy used to dim and warm light, and in that conditions warm white seems just white, and my neutral lights seem cool. It is just easier on my eyes, more comfortable.

Then again, I have a 2700K led lamp on my desk to study, just because I like it, and late at night cool lights don’t seem right to me. In addition, I think it is better if you have to sleep inmediately after stopping studying. In this conditions, the transition from warm lamp to warm flashlight is “seamless”.

Of course, If you like cooler neutral / cool whites then you don’t have to be educated, it is fine. I would try an inexpensive warm flashlight if I were you and had the chance, just to try it if you haven’t, but if you know it isn’t your cup of tea then again it is just fine, personal preference.

An e-switch would probably make this much more complicated to design (double-tube), so I would suggest using a mechanical (reverse/forward) clicky switch.

Not sure if there's a 9 emitter optic with less than 40mm. IMHO, going beyond 40mm will make this light too big and ugly using only one battery. Moreover, there's little benefit to expect with 2 more LEDs, making this light only "more floody" than it is already. :-)

I would also like the center LED to be something for long distance illumination. But I did not find any optic that has multiple beam angles, so something like Osram's White Flat will not work well here. In such a case, a classic multi-emitter reflector might be the better choice but then again the head diameter will become huge. UV LEDs will not work either as their wavelengths will be filtered out by most plastic lenses.

Concerning the tint: Many people here seem to favor a tint between 4.000K and 5.000K. The downside of HighCRI emitters is their worse efficiency but this could be solved by driving an array of six LEDs at reasonable currents, yielding in a beam that is both bright and pleasing for optimum color rendition.

Update:

I revised the OP with the latest draft and some spreadsheet about the specs. An integrated USB-C port might be a nice add-on, too?