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

Are we set on the LEDs?

R9 values and BBL? Is the light going to be spectacular? :slight_smile:

Under 40$, or under 50$ shipped at least seems decent. I hope the interest will be a lot more if it is really that inexpensive.

Does this mean it will be constant current regulated? Is it a boost driver with two strings each with 4 LEDs? Is the intent to run the batteries 1S4P?

At that price point I think I would like to reserve an additional 2, putting me at 3 total.

@stereodude, it is actually going to be using a linear FET instead of 7135s.

This allows for no PWM, perfect constant current allowing for greater efficiency of the efficiency, and no parasitic inefficiencies coming from PWMing 7135s.

Fitting it under 40€ or 39,99€ with shipping, means no import taxes in many countries. That means the light is 39,99 to the door. A 41€ light with tax is more than 55€ to the door.

40€ = 46$

They should charge a few extra bugs.
I don’t want an manufacturer to make loss, like Lumintop on the first round of the GT.

For Germany it’s 26 Euro and a few cents to slip under taxation.

And if I must pay a tax, I am OK with that.

In Poland the limit is €22 for purchases and €45 for gifts.

All Chinese imports are „gifts“. :slight_smile:

Please sign me up for 2 lights

It is a pity there is no LED choice for higher R9 and CRI value.

Thanks Lexel for designing the driver. It looks good. I hope your hand is doing well. Now about that question from The_Driver.

Lexel, you know better than me for sure, because I know zero. But I do know that the led4power drivers have a separate channel for moon mode that uses only a resistor and doesn’t use the FET at all, to get a low enough output. Unless you’ve done something led4power couldn’t/didn’t do to get lower output from the FET, it might not be low enough for some people. For me, there probably isn’t any need for an actual moon or firefly level mode. This is a lantern, with light shining in all directions, not a flashlight with the beam concentrated in one direction.

The lighted switch on a Q8 (and probably this lantern) is bright enough for some purposes. Brighter than firefly, lower than moonlight.
What moonlight in a flashlight means to me is enough to find your way around a room or search for something with night adapted eyes, without the spill disturbing sleepers.

In a lantern this is not a practical aim, as if bright enough to light the room for searching, it is maybe too bright to wave around without disturbing sleepers. In a lantern I think the lowest setting (in warm tints) should enable a sleeper to wake up and immediately grab keys/glasses/flashlight/phone etc left lying around the lantern, but not much brighter than that. I have no idea what this translates to in lumens for a 360 degree beam, but would be interested to find out.

Harder to test I would imagine as well, since the lantern won’t fit many DIY lumens test rigs, and would need a sphere, right?

I guess I’ll put WhitedragonBC down for 1 more, total of 2, 2nd number 962 on the interest list.

lexvegas added two more at 960, 961 on the interest list.

NuggetMcNugget added at 963 on the interest list.

Look like we can hit 1K order for this light. :beer:

Yeah, I think we’ve both got the same idea. I might not have been clear enough though. I think the lowest amount of light that the FET can do will NOT be as low as the classic moonlight levels but WILL certainly be low enough for lantern use.

For this we would need anorher MCU like Attiny 84
I had already to remove Indicator LED output for linear CC regulation

R1/2 Volk age divider for LVP
2 FET channels
Enable for rhe CC OPAs and powerbank

Can someone explain to me how burning the extra voltage above Vf in a FET instead of a 7135 is going to gain efficiency? What are the switching losses in PWM’ing a 7135? The proposed circuit basically uses a FET as a varistor. It’s 2018 and we’re back to using current limiting resistors?

Why isn’t there a true constant current boost circuit? A 1S4P or 2S2P battery config and a two 4 LEDs strings would operate in boost regardless of the battery voltage. This would give constant brightness, ensure each LED gets the same current, and should have greater overall efficiency than just throwing away power in a FET turning it into heat.

I agree, no additional moonlight mode is needed. Still, it’s interesting to see how low it will go.

I have to agree.

To play devils advocate:

Part of the reason may be the costs and complexity, though. Getting the boost driver right would require multiple revisions, especially to integrate it into a firmware like Andruil. Sure, there are dedicated smps ICs out there, but that increases the BOM and manufacturing effort.

For those who really care about such things, the BLF designs are all made to be easily modded, which many will do.