Wow!

[Bort]

@can

@Rufusbduck

First you get a tutorial on the difference between fet controlled and Amc7135 controlled drivers.

An fet is used as a switch. Good ones like we use have very low resistance so when “on” the LED is getting every erg the cell can push through it hence also the desire for low internal resistance high current cells.

A 7135 passes a fixed amount of current burning off any excess voltage over that necessary for the LED at that current as heat.

By adding 7135’s in parallel it’s possible to increase the LED current by 350 mA for each one added. This makes it very easy to dial in a certain maximum current. .35A, .7, 1.05, 1.4, … , 2.8A, etc.

Modes are created for both types by rapidly turning either the fet or 7135(s) on/off and using the width of the “on” period to give a perceived percentage of the total. This is called pulse width modulation or pwm. In both cases on is still fully on so the fet “on” is a brief pulse of everythingthecellshas and the 7135(s) supply pulses 350mA X the number of 7135 chips.

Since LEDs are more efficient at low current it makes sense to generate any modes less than 350mA by pulsing a single 7135 but since an fet has much lower resistance than a pile of 7135’s you get a more powerful turbo by using an fet for turbo and the higher modes.

Both the A6 and SS/Cu lights use an fet +1(7135) driver originally designed by Alex Wells(BLF member wight)following on lots of earlier work by several others(good history lesson there) with the main difference being the processor on the newer version has more memory and can run a more complicated user interface (UI).

Been looking for explanations on drivers for 2 years. This is one I can understand.
It seems like experienced posters talk about drivers in some type of code language using abbreviations etc that is all greek to me. (and I do not speak greek)
I would still like more simple information and I know others also have been looking. Be nice to have a sticky page like this one
LEDs & Other Stuff - (Reference) LEDs & Other Stuff - (Reference Guide)

check out this page, i have not updated it in a while, but anything thats not explained well let me know and i’ll see what i can do

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