SureFire A2 on a single 17670??

I asked myself: is there any LF lamp to put in an A2? YES, there is.... but they are ALL only 4 Volts. So must be driven by one 17670 cell....

As LEDs have a Vf of about 3.5 Volts, I'm afraid the LEDs will not work properly anymore on a single cell! Normally, with 6V, you have plenty of room to drive the LEDs.

Did anybody try this already? In case it doesn't work, the A2 is only usable on 2X 3V cells... because 2X 3.6V will blow the incandescent lamp
Maybe the LEDs will survive 7.2V but the incandescent lamp won't.


Timmo.

The regulator on the A2 needs 6V, IIRC.

2xR123 won't blow the lamp (because of the regulator). There's been people running their A2's with R123's, but nothing definite has been established regarding long-term damage to the LEDs.

Well GreenLED, you just answered my question before I could post it

But what kind of regulation do they apply for the lamp? Is this really a 4V lamp, as this is the only Lumens Factory lamp available?

Then, they could use the linear regulation method, which is wasting energy, or the PWM regulation, which means, pulse width will increase when batteries are getting used up....

I think, I'll be wanting an A2 with white LED's

Timmo.

As the green one said, the A2 will work with two li-ions (7.2V) but not with one. The PWM softstart regulator works as a buck circuit to essentially send around 4.2V to the lamp. The LEDs draw power straight from the batteries and it is the surface resistors on the LED ring (and tailcap) that help drop the voltage into the proper range. If you wish to use rechargeables, there are a few options for protecting your A2's LEDs. 1) You can swap them out with 5mm LEDs that have a higher Vf to handle the increased voltage (ie, MJ LEDS) or 2) You could swap the resistors out for higher value chips to compensate the increased voltage, or 3) you could wait until the new Onion rings become available https://www.candlepowerforums.com/threads/199366

Hello Leukos,

well, you seem to know everything about it! So it's a PWM regulator for the lamp, en the LEDs are simply resistored, so not regulated. That means an endless runtime

Do you know the current per led @ 6 Volts? If this is less than 20mA, the LED-circuitry can be driven at a higher voltage.

Where are these resistors situated? I can easily replace them, being an electronics engineer


EDIT: do you know the lamp specifications (voltage, and current draw) ?
And, last but not least, do you know what current is drawn from the batteries @ 7,2V (should be LESS current than lamp rating....) ?

Timmo.

So wait can I get a definite answer? I can run 2x R-CR123 in an A2 right? why would this be bad for the LEDs?

Solscud007 said:

So wait can I get a definite answer? I can run 2x R-CR123 in an A2 right? why would this be bad for the LEDs?

Click to expand...

Yes.

You're over-volting the LEDs, which means overdriving them, which means they have to deal with excess heat buildup. This can damage the phosphor and/or semiconductor portions.

325, everything you'd want to know (and then some more) about the A2:

thread by js (followed by Part 2)

There's a couple of A2 compilation threads out there as well. Here's one of them: Index of A2 thread