I am planning in designing a flashlight from scratch(mainly to learn new things) but first I want to mod a convoy s2+ as I think its a good starting point. On
my own light I want both a tail and side switch but on the convoy Im cool with only the tail switch but I want it to be an e-switch. This is when I started going through possible designs and decided that a double layer battery tube is not something I want to do. Im not very experienced with electrical engineering but so far the best thing I could come up with is something similar to a switching power supply. I would have two capacitors(or inductors) and switch which one the main power path for the head(driver, led, etc) goes through and the other one which is already charged up would power an mcu, the switch and some kind of power communication protocol(basically send signals through the battery).
My question is would this even work and what do yall think about it? Also Ive looked on quite a few forums and resources and couldnt find a better solution but if someone knows of one please explain how that would work.
You could try a piston drive. Basically have the e switch on the driver where the spring would normally be, and have the physical button be at the tail of the light pushing the battery in order to actuate the switch. Its a bit fiddly to get the dimensions right but I’ve seen someone on this forum do it, I think it was CRX?
Also check out the Fenix WT25R, has a quite unique door and how the from the pcb goes back to the door and on the negative contact, it has two “flat rods” in the corners and they are making contact with the door, and then on the battery’s negative !
This is also a nice design but doesnt work with cylindrical lights. I forgot to specify that in the op. By the way I also thought of making a flat light with two 14500/aa and I wouldve used this kind of design. Sadly it doesnt work well with my current goals.
Get power in the tail cap. Obviously the driver in the head need most of the voltage, but you can either drop a very low voltage in the tailcap and boost it for your controller or take a higher voltage for a very short time. As a result the driver will receive some kind of PWM signal with a very high duty ratio.
The controller in the tailcap has now power. Next step is to send a control signal to the driver. This can utilize the previously mentioned PWM signal as a carrier.
Yeah what I tried to describe in my post was kind of pwm just with smoothing. I also thought of carrying the signal with pwm but it seemed unreliable because of capacitance but I heard that its possible to inject a high frequency signal into a power line(basically a radio signal) and I would probably try to do that. But I guess the general consensus is that you have to go with the pwm to make it work. The other thing I was wondering is how to start it up. The pwm is done by a chip so somethinghas to power the chip before it can sustain itself. I havent found anything that would work reliably. I want a general solution and not something that hinges on some convoluted step-by-step boot process. I think thats what the comercial products do like the wuben t4 for example.
Some of the earlier lights from Nitecore and Jetbeam, like P10, RRT1, which were also constructed this way, with the camera-visible PWM. the Fenix APF tech may be the same way, but without the camera-visible PWM.
Yeah the fenix APF basically does what i will do from what i gather. Nitecore did do something similar but since those years they used non standard batteries and now ribbon cables so you cant even properly disassemble their lights anymore. I want to make my solution standardised enough that it wont lead to problems like this. I want it to work with anduril too, but i have a few plans that wont even need a modification to anduril to work do thats nice.