I’m wanting to build my own driver, I’ve got experience making PCBs. I don’t want to reinvent the wheel so I’m trying to find a proven schematic for a very reliable 3 mode flashlight driver. I like the idea of using an ATtiny13a chip (or whatever is equivalent or better) and 7135 regulators, due to simplicity and reliability. I’ve searched on this forum for an hour or so and can’t seem to find anything. Can somebody please point me to a schematic?
There are a couple of old schematics around, but you won’t find them by searching “schematic” because nobody really talks about them. If you search “driver” and find one you like that is uploaded to OSH Park, then you can download at least the source of the PCB, from which you can reverse-engineer a schematic. In some cases, members also upload schematic files and other relevant info about the driver to OSH Park. I have a few drivers up on OSH Park myself, but I never took the time to upload anything except the PCB source for manufacturing. If you’d like, I can give you an old Eagle PCB file of mine. But there are better driver files available, honestly.
As for modes, you will need a firmware, which you can find around here also. Fortunately, they are easier to get, since ToyKeeper has a repository of quite a few of them, HERE <<<
Alex Wells is BLF member “wight” and unfortunately hasn’t been seen here for almost a year. But the driver you picked doesn’t happen to have any source files uploaded. Only Gerber files are in the download link. I forgot a lot of drivers were done that way in the past. Sorry
Thanks wtf. I’ve looked at it, and would like to modify the firmware to get 3 specific modes, I need 200ma, 600ma and something like 10hz flashing. I’m using this for taking photos of aquarium fish at night, and these exact intensity levels are perfect for this. The flashing confuses them, making them stay still for a few moments, then switching over to the 200ma or 600ma modes would be for photo graphing whether they are at the front or rear of my aquarium.
I’m guessing I wouldn’t even need the mosfet, and I can find a linear regulator in the SOT89 package rated for 300ma, instead of the hard to find 7135 (rated at 350ma). Then I could just use 2 of these 300ma regulators to get my 600ma, is my thinking correct?
If you can find or make a linear driver that has consistent output levels as the battery discharges it should work fine as long as you pay attention to a few details. If the flashlight host is small and needs to be on for a long time the linear driver could lead to overheating as it burns off excess voltage. Next you need to deal with tint shift, it can change a little or a lot with current changes depending on the led’s used, some people prefer pwm just to avoid tint shift. BLF member Mauuka has posted a lot of led CRI tests here.
Bistro firmware uses a “clicky” switch and can be modified if you don’t mind messing around with C programming. You could make a mode for your photography and then change to a normal flashlight mode using the configuration menu, no reflashing needed. Going from blinky modes to normal modes would be awkward, probably easier just to use a separate light for flashing the fish.
It might be better to just buy a complete driver than buying parts from various places and getting beat up by shipping fees. Mountain electronics sells kits and complete 7135 drivers as well as any other components you might need to modify or build a light for your needs. Led4power and Lexel sell linear drivers but delivery times will be longer due to them being on a different continent. Lexel and Mountain also sell good buck drivers which will run cooler than linear drivers.
Almost any driver that is made for a single cell lithium battery will work with that voltage range. The photography you plan on doing is what makes it tricky. Most flashlight firmware is designed to keep flashing modes separate from the regular modes to avoid accidentally activating them, so going from flash mode to lighting mode may not be fast enough.
A good picture requires good light so you need to research what leds will look good at both your intended power levels. If the light will be on a short period of time or the light is capable of dissipating the heat developed at your power levels overheating is nothing to worry about. Linear drivers and fully charged batteries are the worst combination for making heat which may or may not be a big deal for you.