What makes the L4 the L4 DIGITAL Lumamax?

Is there something digital inside the L4 or is it just the name?

I know there is regulation, but is it digital regulation?

Well,
I had exactly one computer course and I was taught that all computers communicate in binary which is know as digital code. So, if there is an IC in there it works off of binary which in turn is classified as digital, cause all IC operate off of binary (digital) code.

Like I said I don't know too much about computers.

Digital is a pretty imprecise term. All it really means is that the device in question uses discrete states instead of continuous variations. It doesn't even have to be binary, though that is commonly associated with digital logic. The L4 qualifies in the simplest sense because it has an on/off switch and not a dimmer. I think Surefire is using it to mean that the on state is regulated, so it's either on or off instead of on at xx% of maximum brightness or off.

A fundamental part of digital circuitry at the low level is distinguishing between on and off. Voltages in a certain range are all considered on, and those within another range are considered off (anything else is noise). As signal degrades, various components will filter that signal back into a nicely polarized state. That's essentially what the L4 regulator is trying to do--if there's enough juice in the batteries, crank it up to a consistent, level output (the on value), basically a high-pass filter. Presumably it does _not_ do the opposite, i.e., drop the output to zero when there's not enough juice for a one, but there is still adequate parallel between what an L4 does and conventional digital circuitry to warrant the name.

- Russ

Actually, I believe that the L4 is digital in the straightforward 'thars a computer in thar' sense.

A voltage regulator is not in and of itself a digital device. Most voltage regulators are purely analog devices, and simply maintaining a particular output voltage is not enough to call something 'digital'.

Willie Hunt is the designer of the 'LVR-3', a PIC microcontroller based voltage regulator for incandescent lights. He developed it to regulate the power going to his headlamps for caving. If you search for LVR-3, you will find his site. The device literally measures the battery voltage, stores that number in a computer, and then generates a pulse width modulated output that produces a nice regulated RMS voltage to the lamp.

Several years after developing the LVR-3, Surefire hired Mr. Hunt, and in the next year came out with the L4.

I've never taken an L4 apart, but I have built LVR style circuits. They are true digital beasties.

-Jon

r2 -- an unusually clear statement of what's going on -- Paul

Ummm, I answered this question eons ago when the L1 came out. I have an issue with calling it digital, but that's only because I'm a purist. These days, the term "digital" is so overabused, mainly because of marketing types who know nothing about what the word means. If you have an HC04 in there, that's carte blanche to calling it digital even though a SMPS is mainly an analog circuit. If you read the basic principle behind a switching regulator, it is an analog circuit. However, it's controller may be analog or digital (micro controller). In the case of the L4, I think they are using an integrated contoller from one of the big 3. To use a micro for a light and not give it dimming features is a waste.

So far, the Arc LS4 (no relation to the L4) is probably going to be the first Luxeon hand torch controlled by a microcontroller, unless Surefire pops us a surprise. To me it would be acceptable to call that flashlight digital. There are other reasons why I would call it digital but I can't get into that.

CM

Personally, I think the word is mostly used for advertising purposes. I mean DIGITAL sounds way cool, especially if engraved on your flashlight! Who wouldn't want to show that off to friends?