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

Thank you :slight_smile:

Should I take a shot at making code for this driver even though I don’t have the hardware to test on? At least then Barry & Co would have something to flash on the MCU.

I can’t guarantee it would work, but … it might.

I can probably get the tint-control stuff working, at least, since that seems to use pretty standard PWM. But I’m not sure about powerbank functions. I need more info about what the USB and opamp enable pin is supposed to do. Lexel, how should that work? Does the pin enable both the USB powerbank circuit and the primary LED output? I’m not sure if the pin needs to go high for regular LED modes, or for powering other devices, or for charging the lantern itself, or a combination.

I believe Lexel offered to build a test driver, (at an unknown cost, which i am unable to dedicate any large amount of funds to at this time) but i believe Barry was going to have their engineers look at the driver design specs Lexel sent me to see if they can build that FET driver posted earlier. Then it may be possible for them to build some test units to send you. (building the driver is out of my ability range) but you can contact Barry or Lexel directly if you want to get more info on the driver hardware.

@listbot add 1

Put me down for one, maybe two.

@listbot add 2

im interested in 2 lanterns

[quote=sbslider]

It appears the “live” version isn’t being updated?

Last entry I see in the google doc is 979 CrashOne from post 2587

I took a short break from updating the interest list as I have been on vacation, and now work travel. Also I was hoping the listbot would pick the job up but it appears to not be working. I will comb the thread over the next few days and get caught up. I apologize for any inconvenience or burden this has caused folks.

No worries at all on my end. Just thought it would be worth mentioning. Probably easier to catch up now than in a couple of months :slight_smile:

Definitely. I went through that once already.

I still have to post the one you sent me last week, ( i been a bit overloaded with work this past week or two.)

That disappoints me, I think this is the last thing that needs a FET instead of well managed linear drive. Either one, or two, or even three banks of 7135s. Even just one bank with PWM. Not many 7135s needed to achieve desired lumens.

Which would be more consistent throughout the cell discharge, assuming suitable LED Vf, as well as much more efficient (run-time).

ISTR that the prototype uses the Q8 driver with the FET disconnected and a NanjG 7135 driver connected to the gate pin instead, as a second 7135 bank.

Also not sure how it fits in with the two different sets of colour temp LEDs and mixing. I don’t see how a FET has any purpose in that arrangement, just two banks of e.g. 7135s, one for the lower colour temp LEDs, the other for the higher.

Perhaps a FET could just override any of that subtlety and give “Max Power” for those who insist (maybe they shouldn’t be buying a practical lantern).

The only point of a FET is to (over) drive the LEDs to the absolute max. that the particular combination of cell max. current and ESR, state of charge, LED transfer characteristic etc. can deliver. In short blasts. Inefficiently. Sure, wind it down with fast PWM but that will make no difference to the inefficiency (short run time and inconsistent output as the cells discharge).

To summarise: why does this lantern need a FET driver ?

But I am not on the interest list, just an observer, so crack on please.

I hope I have mis-understood.

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