high PWM vs low PWM:
Why do many flashlight makers use low PWM?
Is it that lower PWM make the light use less current, therefore has a longer run-time?
And if so, does anybody have done any test of how much of a difference it makes if the light uses a higher PWM vs a lower one?
(I`m talking about run-times)
I almost think they do the low pwm to offset poor conductive materials they use because it’s cheap. Doing the low pwm will keep the runtime high with cheap materials I guess. Not sure about that at all, just speculating.
In theory, the current used is exactly the same. In real life, it's still very close, the difference being really small due to inherent capacitance/inductance of the circuit used.
Seriously I think the programmers simply did not realize people are bothered by it, and does not bother to do the extra work. Programming high pwm is just a little slightly more complex.
For example, you have 100 on/off sequence. You need 50% of the light output. You either do program either:
Code 1. Sequence 1 ON, 2 OFF, 3 ON, 4 OFF, 5 ON, 6 OFF... and so on. Need to figure a way how to put this as code. Not very hard but still, compare with Code2 below
Code 2. Sequence 1-50: ON, 51-100:OFF. Easy. No thinking required.
Sure Code1 has much smoother output, 50 times higher PWM than Code2, but both will still have duty cycle of 50%. A programmer who couldn't care less would probably just key in Code2 and get it over with.
Capacity will increase current draw slightly at higher pwm frequencies.
The other problem with high frequency is getting a low duty cycle, it is enough to get 1% on a 100Hz pwm, that is 0.0001 second (100us), but on a 10kHz pwm it is 0.000001 second (1us), that might not be possible on a cheap microcontroller.
For lights with the pwm in the tailcap the problem is even larger, because the converter has to start and stop for each pwm cycle, that is not possible for a 1us cycle. The solutions is to use lower pwm frequency or not make the low very low.
Thanks for the info…
I had to read these explanations a few times, and still I`m not sure if I got it.
1 thing that I didnt understand is HKJ, you said when the PWM is in the tailcap?!?
What does that mean? (is that with electronic switches?)
I`m just asking, because I have and SF low voltage drop in, but the PWM starts to annoy me a bit.
A few lights has a mode selection switch in the tailcap in addition to the on/off switch, one way (but not the only way) to make this work is by putting the pwm electronic in the tailcap. This is the case with Olight M20S and some other lights.
Okay gotcha! thats seems to be with more expensive lights then.