how does the a2 work?

[turbodog]

I just got an a2 the other day. How does the dual brightness work? Where is the regulator? Etc.

 

[this_is_nascar]

I surprised someone would spend that kind of money, without least understanding a light a little bit. Dual brightness is obtained by the dual-setting tailcap. Press slightly for LED usage and press harder for the incandescent. The regulation circuit is contained within the body tube.

 

[Chris M.]

From what I can tell, and please correct me if I`m wrong:

The regulator is in the top of the body next to the head. The regulator part feeds the lamp while the LEDs have a simpler resistored drive method. Both share a common ground, and are always connected to the electronics when the head is on. The 2-stage tail cap contains a resistor, which is connected in circuit when pressed only partially. This completes the circuit but limits the voltage avaliable to the reguator, meaning it will not switch on. The LEDs do however, since they bypass the regulator. Press the tail cap harder and the resistor inside is shorted out allowing the full battery voltage to pass to the regulator circuit. Now having enough voltage, it switches on, but the LEDs remain on too (just get a little bit brighter). When the battery voltage runs down to the point where the regulator cannot sustain the output any more, it shuts off, but the LEDs remain as they do in low-power mode until the power gives out completely.

Sounds complicated, but is a very innovative and surprisingly simple engineering solution to a potentially complex problem. Assuming I got it right that is.

/ubbthreads/images/graemlins/grin.gif

 

[this_is_nascar]

[ QUOTE ]
Chris M. said:
From what I can tell, and please correct me if I`m wrong:

The regulator is in the top of the body next to the head. The regulator part feeds the lamp while the LEDs have a simpler resistored drive method. Both share a common ground, and are always connected to the electronics when the head is on. The 2-stage tail cap contains a resistor, which is connected in circuit when pressed only partially. This completes the circuit but limits the voltage avaliable to the reguator, meaning it will not switch on. The LEDs do however, since they bypass the regulator. Press the tail cap harder and the resistor inside is shorted out allowing the full battery voltage to pass to the regulator circuit. Now having enough voltage, it switches on, but the LEDs remain on too (just get a little bit brighter). When the battery voltage runs down to the point where the regulator cannot sustain the output any more, it shuts off, but the LEDs remain as they do in low-power mode until the power gives out completely.

Sounds complicated, but is a very innovative and surprisingly simple engineering solution to a potentially complex problem. Assuming I got it right that is.

/ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

... yea, that too.

 

[turbodog]

TIN: yeah I understand the principles of the light. I have read a lot of posts about it. I even remember you selling a trashed one from a botched dissection.

CM: This sounds plausible.

With the soft start and all... what kind of bulb life are people seeing?

Also, it seems that if the main battery spring is not in spec (length), this could affect the lock out/led/main modes.

 

[Size15's]

Inside the A2:

BTW, this is a functioning flashlight (only two of the LEDs light up though)

Al

 

[turbodog]

If you look on the circuit board with the leds you can see some surface mount parts.

 

[Chris M.]

Nice photo Al! That`s pretty amazing that it still works too, though I *am* dissapointed they didn`t cut the batteries in half too so we can see what`s in them as well /ubbthreads/images/graemlins/tongue.gif

<font color="800080">If you look on the circuit board with the leds you can see some surface mount parts.</font>

Those are just resistors to limit the current to each LED. The board is otherwise "dumb", connecting with the electronics inside via the outer contact of the lamp assembly. Looking closer at it, I believe actually the two units (LED ring/lamp) share a common positive, with the bottom contact of the lamp being negative and connected to the regulator circuitry, while the body provides the negative return for the LEDs right back to the tail cap.

/ubbthreads/images/graemlins/grin.gif

 

[Size15's]

Quite how I was able to take the photo whilst holding the A2 with both hands I'm not sure. I believe it's a Shelby Chan Photo.

Al

 

[chamenos]

impressive /ubbthreads/images/graemlins/ooo.gif the A2 is currently still my EDC /ubbthreads/images/graemlins/grin.gif