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

I had originally planned on the 7135s, but left the driver & firmware for that part in the lands of Lexel & Toykeeper as they know much more than i do about driver design & circuits. Maybe chat with them about your thoughts on it.

You have misunderstood.
The point is to have linear driver. But instead of a bank of 7135s it should be based on a FET driven in linear mode.
This won’t be a hot rod driven as far as batteries allow but a nicely regulated light.

Good to hear that. that’s the way to go.

I didn’t realise that Lexel had developed a linear variable driver (using a FET, but that’s not the important bit).

AFAIK only Led4Power has a proven one at the moment.

@listbot add 1

I am a real fan of minimizing power losses (e.g., most lumins for the longest time). I don’t care what color the light is. I am one of those that view this as an emergency lamp. If I understand what is being debated, FET + PWM yields the best use of battery resources vs a whole bunch of analog devices. And reduces extraneous heat generation.

I remain a: No holes in the light, no charging of external devices, no charging of internal batteries. It is a light. It has batteries. Stop there. That is a lamp.

Having AM radio could be a nice addition tho

I think a bunch of lanterns like this would come in pretty handy around here the next few days (weeks). - From the NC coast.

To build one prototype driver
about 17$ Oshpark with slow shipping for 3 boards
Order parts I do not have stocked 20$ With shipping costs
5$ parts I have stocked
6-7$ assembly time
5$ testing time
DHL express to china 35$

But if they make it in China its cheaper and faster to make one

When the light goes in production we can talk about free samples or a payment for the design, at the moment funds for me building a prototype would not speed it up

@Lexel: What are the specs of the power bank circuit in the final design?

For instance:

  • Max. output current to USB devices
  • Charge rate of the lantern batteries
  • USB output type: e.g Type-A with BC1.2 DCP / Type-C with PD 2.0/3.0
  • USB input type: e.g microUSB 5V / Type-C with PD 2.0/3.0
  • Possibility of using the lantern while being charged
  • Possibility of using the lantern while charging external devices

Thanks for the clarification and keep up the good work :slight_smile:

Table 4. Charging Parameter Default Setting
DEFAULT MODE bq25895
Charging Voltage 4.208 V
Charging Current 2.048 A
Pre-charge Current 128 mA
Termination Current 256 mA
Temperature Profile Cold/Hot
Safety Timer 12 hour

USB type is mechanical of the light not driver
max. USB out of the chip is 2.4A but this gets reduced by a resistor on DELs layout as I understood to 1.5A
Batteries get charged with 2A as we do not use the chips internal bus

the chip supports up to 5A, but likely the Powerbank chip needs to be programmed differently not sure how that works

Lantern can be used while charging/discharging,
there is an enable pin from MCU not sure how this will be configured if output is enabled or not when the lantern is off

@listbot add 1

Pleaae put me down for one (this is the reason I just joined BLF 5 minutes ago).

After reading much of this thread, I have been looking for this lantern for the longest time!

Yeah, I’m sure they would. But any light capable of lighting up a room well enough to see will be handy, TBH. This storm likely won’t care if you have DBSAR lanterns or Q8’s with a Styrofoam cup on top as a makeshift diffuser. :wink:

EDIT: Oh yeah, if you’re at the coast, you should really evacuate if you can. Sadly, some people can’t or won’t. I’m pretty far inland at Salisbury, but it’s probably going to get interesting here too, if Florence goes as predicted.

definitely understandable. ( especially with the higher cost of shipping to the China engineers.

No, you have that the wrong way around. FET+PWM (or in DC FET= “Turbo”) is the least efficient way of driving an LED. But can give spectacular output when over-driving LEDs. Irrelevant for a lantern, actually undesirable.

Look at all the chatter about which FET, cell, LED, host, reflector, MCPCB, copper addition, spring mods. etc. can, in combination, give “Max Power”—-) for a few seconds before they overheat. Really not relevant for a lantern IMHO.

FET+1, the staple BLF driver architecture, uses 7135 linear up to 350 mA, then the FET kicks in (inefficiently) above that. The single 7135 also allows the efficient firefly and moonlight modes that would not be possible with just a crude FET. And would have some utility in a lantern.

Linear drive, typically using a bunch of 7135s, either banked up in sophisticated manner like Mike C does, or double-down or triple-down, or just one bank sized for max. output, with fast PWM to dim down, is a decent compromise of efficiency, cost, complexity, ease of design.

Personally I wish the 7135 had never been invented. It has stifled innovation for so many years because it works and scales so well, and is inexpensive. Due to being cloned (sometimes well, sometimes not) by so many others (I don’t even think AMC exists any more).

What Led4Power is doing is much more clever, but proprietary. And I fully agree it should be proprietary, speaking as a professional electronics engineer who has to make a living.

This has always been the case for BLF hardware, there is a great reluctance to actually publish schematic diagrams and bills of material for review and critique, I have mostly had to reverse-engineer them from e.g. the OSHpark layouts.

I see that this is also the way that some BLF designers are now working, in some sort of collaboration with manufacturers. Be it hardware or firmware. And I support that. OSHpark and the various open source software models are fine, but not something that I particularly embrace. Engineers should be paid for their efforts by commercial manufacturers, no matter how derivative they are.

If they choose to give away their unique innovations, circuit design, algorithms, hard-won empirical knowledge, that’s down to them (I would not). If they simply re-purpose derivative works from others, that’s down to their conscience as to whether they also acknowledge their inspiration.

Decent work should be rewarded. Whether financially, or by seeking popular acclamation, or the worthiness of “charity”, or otherwise.

Motivation is a complicated subject, particularly on social media like this, we are all different, there are no simple truths.

What’s wrong with having things which are good, cheap, and easy? A thing doesn’t have to be difficult or expensive to be worthwhile.

One could also argue that it enabled hobbyists to innovate because it lowered the barrier to entry; without it we might not have any of the cool stuff we have today. Or one could argue that aluminum shouldn’t exist because it’s too good at too many things, and it’s cheap, so it has stifled innovation of more interesting materials.

Open-source doesn’t mean not getting paid. It’s free software because it’s free as in speech, not free as in beer. Here’s a summary of the two main models for these things:

  • With proprietary software, you get what you pay for.
  • With open-source software, you get what you pay for, everyone gets what you pay for, and you get what everyone pays for. More people get more value without individually having to pay more, and its openness reduces the risk for everyone involved.

Conscience… and the license. Attribution is legally required in almost all free software licenses, because it’s a necessary part of making copyrights work.

Thanks TK. I wanted to say something but I knew I couldn’t do it justice. I was hoping you’d come along. :crown: :+1:

+1 …. now that’s funny~

This :slight_smile:

There is no equivalent to the software model licences as regards hardware.

Which, I think, is why there is this reluctance to put up schematic diagrams and BOMs here. Most seem to be copies of application note circuits, when studied. At most we get a link to an OSHpark layout to reverse-engineer.

Circuit designs cannot be protected the same way as code, AFAIK. Certainly not the type of drivers we have, even the most esoteric, it has all been done before, they really are not very complicated.

By the way, with all the SW open-source models, has anyone ever exercised their rights if they thought they were being ripped off ? Perhaps they have, maybe they got somewhere, I don’t know, not my area.

And, to be frank, it is the hardware that costs actual money and is the most important thing for manufacturers to optimise. Just saving a few pence by removing or using lower spec. (but still satisfactory) components, or innovative circuit design, intelligently is of great interest to manufacturers.

If the code source is given away for free (but, hopefully you get paid for adapting it to the device) that’s fine by me.

But hardware design, component selection, PCB layout, prototyping, testing, requires expensive tools, skills, knowledge, time, expert materials procurement etc. to do it properly, and is a rather rigid discipline. Not something to be dipped in and out of.

Or done remotely, from a WiFi laptop anywhere in the world. You actually have to check in to the Lab and use the (very expensive) kit to see what’s actually going on.

Quite different from simply connecting a clip and having a few goes until you have something workable.

The PogoPin connector will be transformational I hope.

:person_facepalming: