*BLF LT1 Lantern Project) (updated Nov,17,2020)

It’s the LED itself. Lower current = more lumens/W. Some of it is due to less heat (which I think does not change significantly with or without PWM) but I believe some of it is intrinsic to the conversion of electricity to light. And that part means more efficiency by running at say 1 mA than at 100 mA with 1% duty cycle.

And the PWM we talk about here is not the PWM of power supplies. It’s a duty cycle for a linear regulator… nothing efficient about it. Some drivers do have more efficient design of course, much like modern power supplies.

One last thing: I don’t know about the LEDs being discussed here but some change tint and probably CRI too depending on current. So a linear driver might not be desirable at all because of that.

And I learned most of that around here. Couldn’t dig up the exact threads but djozz’s LED test threads are usually a good place to start to read technical discussions. So are the driver design threads. Unfortunately some of it may be lost in other places. Stick around and the information will eventually percolate lol

@DBSAR, I have already spoken to Sofirn about the bin tints and LED tints to use with the right order code. That was a WHILE back though, so they may not remember about it.

However, if Barry can confirm which LEDs they’re using, they should be these, if I’m not wrong:

–5000k LH351D 90CRI (Part number: SPHWHTL3DA0GF4RTS6)

–3000k LH351D 90CRI (Part number: SPHWHTL3DA0GF4VPP6)

@sbslider, this is in regards to the type of linear regulator used. It can either be a single purpose linear regulator, like a 7135, or a FET used as a linear regulator

FET as a linear regulator, will always be better, but let me explain.

- A single purpose linear regulator will run at a constant current set by its specs at 350mA.

  • If ran at 100% duty cycle, the linear regulator will output 350mA to the LED.
  • If ran at 50% duty cycle, the linear regulator will output AN AVERAGE OF 175mA, meaning the LED will still see 350mA, but at half the time. This is what we usually do in linear drivers. However, they don’t behave well at thousands of hz, and the efficiency of the LED stays constant, even though the average current will be lower. While in fact, it should be more efficient.

This is where the FET as a linear regulator is very useful, rated at say 350mA.

- If ran at 50% duty cycle, it will output a constant 175mA, meaning the LED will now see 175mA, and its efficiency will be increased at lower current, along with the FET easily handling 100s of kHz of frequency, removing parasitic inefficiencies.

The major downside to the 2700K is the significant drop in efficiency compared to the 3000K. I’d prefer 2700K of they were the same or close, but would prefer efficiency since they are not.

@ BlueSwordM and fixed it, thanks for the explanations. I definitely have noticed that LEDs get way less lumens/mA (or lumens/W) when they are driven very hard. But I was under the belief (perhaps, or likely wrong) that at lower drive currents, the lumens/mA curve was pretty constant. So with 4 LEDs each drawing 350mA (fairly low current) the efficiency of the 4 7135s can be no worse than the efficiency of a single FET. But at lower currents, if the switching performance of the 7135 is lousy (sounds like a great BLF improvement project!!) then I can see where the efficiency of the single FET would be better.

Me thinks so

Isn’t Texas Commander the right driver?

please put me on the list for one…

We need a dual channel version of that.

unsubscribed

I have less interest in Lumintop than they have in their customers

Huh? Lumintop isn’t building the lights, it’s Sofirn actually.

Then I’m happy and disregard my Lumintop warning. :slight_smile:

I don’t know what Lumintop did to offend you, but it would be great if you could stop spamming every single thread. If you have something to say, make your own thread and say it.

Kingjohn added to the interest list at number 957

first request was just 2x4AMC driver

added Powerbank stuff

CC regulated MOSFETS

7135s removed
CC regulated without PWM added
LDOmadded
indicator Led removed for voltage divider

Wow. I’m up for that one!

Looks like the surgery didn’t slow you down? Very impressive. Thanks for your all your efforts!

Nice! Thanks Lexel!

WOW :+1: :beer:

Nice job, Lexel! Thanks!

If I could buy these guys a beer I would buy them a bar. Thank you all for making this come true!