loneoceans
Newly Enlightened
- Joined
- Jan 8, 2017
- Messages
- 9
Hello CPF,
Hope that everyone has been having a good start to 2020. A few months back, I was toying with the idea of building a more sensible everyday driver, compared to my (admittedly impractical) GXB high power drivers which some of you may have seen.
Some of you may have seen this thread on BLF about a switching driver I was thinking about, with the main goal of developing an open-source, high efficiency, constant-current driver, using community firmware.The motivation also came from the fact that there didn't seem to exist many high efficiency drivers around, almost all drivers being linear drivers with some combination of 7135s + FETs (though they do have the benefit of low cost and ease of use).
I received a lot of great input from various forum members - many thanks to them, including ToyKeeper for her suggestions and advice especially relating to the firmware side. I've tried to find some time to work on this project on and off, and so far I think there are some developments worth sharing at this point.
Here's the first prototype of what I'm calling the lume series of drivers. This is the lume1 driver, designed specifically for use with the 18650 FW-series of flashlights like the FW3A or FW3C, and therefore has a 22mm (21.7mm actually) diameter. Components were specifically chosen to fit in the very low z-height of the FW3 flashlight, and the inductor only just clears. Certainly a bigger one can be used in other designs for even lower DCR.
Above - the lume1 CC-BB+FET driver. For those wondering about the PCB, I used OSHPark's new AfterDark option which is very pretty. Black substrate, clear soldermask, ENIG finish.
PCB design of the lume1 LED driver; designed with low cost assembly in mind (all on one side, PCB only has 2 layers)
The FW3x was chosen as an ideal candidate for this driver due to its very compact size, great popularity, and high quality construction. The E-switch design is nice too, since it allows for a very clean assembly. I thought it would be a good match for this driver, though obviously the lume topology is easily adapted to any flashlight, and more designs will likely be in the pipeline once lume1 has its bugs worked out. Hopefully this may be a driver that hobbyists will consider when modding their flashlights.
Question for you all: I'm trying to find the battery spring that the FW3A driver uses - it's very nice in that it compresses to a low height is fairly stiff, appears to be silver coated, and has fairly thick 0.8mm wire, making an ideal low-DCR spring. I can't seem to find an ideal off-the-shelf spring so far. I contacted lumintop but received no response yet.
lume1 Driver Feature List
Here are some of the general features. In no particular order:
Driver Development
As with all the drivers I've made, I built a simple development platform to evaluate the original design I had in my head.
This allowed me to evaluate the CC-Buck-Boost + FET topology, and also do some basic firmware testing on the 1634.
Notice that the choice of MCU is the exact same one as used in some Anduril flashlights, such as the Emisar D4 V2. The idea is to keep the design and pinout as similar as possible to enable easy portability of Anduril and similar community firmware.
Right now the target firmware is Anduril. Some modifications need to be made in terms of:
To keep things simple for the dev. board, I soldered a LH351 LED directly on the board for easy testing. Fortunately, all hardware was tested to work as intended and the driver regulates well at 3A output across a variety of input voltages.
With the topology verified, a form-factor PCB was created and assembled. Notice how all the components are only on one side. The spring wasn't installed yet in this photograph. For those with a keen eye, there is one downside to the FET drive, in that current still goes through the low-side current sense resistor, so max turbo is diminished slightly compared to regular FET drivers. I think this is still OK, since typical Turbo drive durations are around tens of seconds before throttling is required to prevent the flashlight from melting!
For the first build, I was able to purchase a copper FW3C flashlight. The flashlight will be built up with either SST20 LEDs or Nichia 219Bs, and fitted with the lume1 driver for more evaluation. This is currently in progress, and I hope to post more updates soon (though the next few weeks will admittedly be a little busy for me). I also just received an FW21 - the larger battery allows for even longer run-times, and I think would make for a great candidate for a lume driver as well.
Here's a preview of things to come:
For those concerned, I did put some tape around the flashlight so as not to have it scratched by the clamp. I think this PCB colourway works quite well with the FW3C.
Hopefully this will be a driver which people will find useful. :candle:
I'll greatly appreciate any feedback and suggestions. Is this driver something you think would be useful, or completely useless?? I'd love to hear your thoughts. I know I'll be swapping out my FW3x drivers for this one though, since preliminary tests with my dev platform have gone quite well.Thanks for reading!
Hope that everyone has been having a good start to 2020. A few months back, I was toying with the idea of building a more sensible everyday driver, compared to my (admittedly impractical) GXB high power drivers which some of you may have seen.
Some of you may have seen this thread on BLF about a switching driver I was thinking about, with the main goal of developing an open-source, high efficiency, constant-current driver, using community firmware.The motivation also came from the fact that there didn't seem to exist many high efficiency drivers around, almost all drivers being linear drivers with some combination of 7135s + FETs (though they do have the benefit of low cost and ease of use).
I received a lot of great input from various forum members - many thanks to them, including ToyKeeper for her suggestions and advice especially relating to the firmware side. I've tried to find some time to work on this project on and off, and so far I think there are some developments worth sharing at this point.
Here's the first prototype of what I'm calling the lume series of drivers. This is the lume1 driver, designed specifically for use with the 18650 FW-series of flashlights like the FW3A or FW3C, and therefore has a 22mm (21.7mm actually) diameter. Components were specifically chosen to fit in the very low z-height of the FW3 flashlight, and the inductor only just clears. Certainly a bigger one can be used in other designs for even lower DCR.
Above - the lume1 CC-BB+FET driver. For those wondering about the PCB, I used OSHPark's new AfterDark option which is very pretty. Black substrate, clear soldermask, ENIG finish.
PCB design of the lume1 LED driver; designed with low cost assembly in mind (all on one side, PCB only has 2 layers)
The FW3x was chosen as an ideal candidate for this driver due to its very compact size, great popularity, and high quality construction. The E-switch design is nice too, since it allows for a very clean assembly. I thought it would be a good match for this driver, though obviously the lume topology is easily adapted to any flashlight, and more designs will likely be in the pipeline once lume1 has its bugs worked out. Hopefully this may be a driver that hobbyists will consider when modding their flashlights.
Question for you all: I'm trying to find the battery spring that the FW3A driver uses - it's very nice in that it compresses to a low height is fairly stiff, appears to be silver coated, and has fairly thick 0.8mm wire, making an ideal low-DCR spring. I can't seem to find an ideal off-the-shelf spring so far. I contacted lumintop but received no response yet.
lume1 Driver Feature List
Here are some of the general features. In no particular order:
- Input - 1S, e.g. single 18650, specifically since this was designed for the FW3x flashlight (5.5Vmax to 2.7V)
- Output - designed for 1S LEDs (e.g. 1S for FW1x, 1S3P for FW3x etc)
- Regulation:
- 3A Output Constant Current Buck-Boost - slightly higher regulated drive than the stock 7+1+FET FW3 driver
- FET on-board for Turbo Drive
- 21.7mm Diameter
- 2 Layer PCB, Single-side Components for low cost fabrication and assembly
- Very low stack height to fit in small driver space for FW3x
- Attiny1634 Microcontroller running ToyKeeper's Anduril Firmware
- HarleyQuinn's Pogo-pin Programmer compatibility
- Efficiency >90% for low to high-mid modes depending on input and output, needs more measurements
- External temperature sensor IC
- E-switch usage (for FW3x) and some hardware debounce filtering
- Low quiescent current for long standby times given that this is an E-switch driver
- RGB outputs for optional LED aux board
- 4 additional solder jumper pads (no FW use for them yet, but it's an option)
Driver Development
As with all the drivers I've made, I built a simple development platform to evaluate the original design I had in my head.
This allowed me to evaluate the CC-Buck-Boost + FET topology, and also do some basic firmware testing on the 1634.
Notice that the choice of MCU is the exact same one as used in some Anduril flashlights, such as the Emisar D4 V2. The idea is to keep the design and pinout as similar as possible to enable easy portability of Anduril and similar community firmware.
Right now the target firmware is Anduril. Some modifications need to be made in terms of:
- HW definitions (pinout is very similar to Emisar D4V2)
- Temperature sensing - default we can still use the internal MCU sensor, but can also take use of external temp sensor
- Control line (use 7135 control signal to buck boost control line)
- Battery Sense (uses simple voltage divider here instead of VCC)
To keep things simple for the dev. board, I soldered a LH351 LED directly on the board for easy testing. Fortunately, all hardware was tested to work as intended and the driver regulates well at 3A output across a variety of input voltages.
With the topology verified, a form-factor PCB was created and assembled. Notice how all the components are only on one side. The spring wasn't installed yet in this photograph. For those with a keen eye, there is one downside to the FET drive, in that current still goes through the low-side current sense resistor, so max turbo is diminished slightly compared to regular FET drivers. I think this is still OK, since typical Turbo drive durations are around tens of seconds before throttling is required to prevent the flashlight from melting!
For the first build, I was able to purchase a copper FW3C flashlight. The flashlight will be built up with either SST20 LEDs or Nichia 219Bs, and fitted with the lume1 driver for more evaluation. This is currently in progress, and I hope to post more updates soon (though the next few weeks will admittedly be a little busy for me). I also just received an FW21 - the larger battery allows for even longer run-times, and I think would make for a great candidate for a lume driver as well.
Here's a preview of things to come:
For those concerned, I did put some tape around the flashlight so as not to have it scratched by the clamp. I think this PCB colourway works quite well with the FW3C.
Hopefully this will be a driver which people will find useful. :candle:
I'll greatly appreciate any feedback and suggestions. Is this driver something you think would be useful, or completely useless??
I'd love to hear your thoughts. I know I'll be swapping out my FW3x drivers for this one though, since preliminary tests with my dev platform have gone quite well.Thanks for reading!
