No, the flashlight app uses the 2 camera LEDs. It works very well and is super bright. Bright enough to be used as a proper torch light at night. Can easily light up an average sized living room.

Ah, ok then. Progress? I'm curious how fast battery life decreases with that on, but not enough to risk burning my flash LEDs. Anyone run this for 10 minutes and compared battery percentage before and after?

These are fairly basic LED emitters.

From my experience with LED flashlights (my site = www.jayki.com), these low powered dual LEDs should not use too much power whatsoever. It might shorten the runtime of the phone by about 5% max. No more.

While I'm typing this, I've left the LED on.

Ran lshal | grep percen;date on it before i turned LED on.
LED on for 10 minutes. (had LCD screen on for about 4 mins)
Ran the same command. Not even 1% battery drop. Nice.
After 15 mins, 1% dropped. But that's probably normal even without LED turned on. =P

btw, I get 25 lux in my lightbox which I use to test flashlights.
Comparatively, that's about 15-20 lumens. Very useful amount of light.

Thanks for testing and reporting. It confirms my (surprising, at least to me) rough calculations from a while back: http://talk.maemo.org/showpost.php?p=345654&postcount=5

My main concern was burning up the flash LED but if it's only putting out 20 lumens, that's not likely to be an issue, either. Cool beans. I'll have to install that; it could be very useful. Also, will it work while the video camera is on?

you all worried about the life of led's need not worry, because leds will last longer than incandescent bulbs, ie for about 10 years, who cares they will last WAYYYYYYYYYY longer than however long you have the phone. dont worry about it. and as for the battery, if youre worried about it, turn the phone off.

LED's generally consume 50mW (mili watts) of power each and have a lifetime of 10-100 years. That is unless they are overpowered much like overclocking. Sometimes people will use more power to get a brighter LED at the cost of lowering the life span of these things which I was curious if Nokia did to get a brighter instantaneous flash.

Anyways, with two LED's in the unit you should be consuming 100mW which is similar to WiFi power usage at it's highest point of transmitting. So, I would guess you should be lowering your all day power level by about two hours if you left them on.

You've never built an overdriven power LED bike light, have you?

It actually surprises me more that Nokia doesn't overdrive these in flash mode, as they are too weak to do a proper job as a flash. The only two reasons i can think of for them not doing so are so exactly this kind of usage could be enabled without destroying them (or maybe they actually did consider video usage), and to avoid shifting the color tint. The latter would be a fairly comical reason given how awful the tint of them is to start with.

Edit: I'm sorry to report that whenever the camera app is active, the LEDs turn off, regardless of the setting of the flashlight applet. Still, a very handy little applet.

LED's light itself doesn't generate much heat unlike the incan lights. However, the emitter itself does generate heat to a certain point. High powered LED's can generate hand-burning temperatures. But these lower powered LEDs generage negligeable amount. So it should in theory never burn out in our lifetime. But still, I don't recommend leaving it on for more than about an hour at a time just incase it does generate some heat at the back of the emitter and cannot dissipate it fast enough. (Nokia probably didn't design them to be left ON for longer than a few seconds at a time anyways)

I don't think the LEDs will burn through the battery too much, but running them for too long may cause other problems--I'm not sure what, but speculate maybe burning out the LEDs themselves (?). I stumbled across this in the kernel source from kernel-2.6.28/arch/arm/mach-omap2/board-rx51-camera.c

It appears to indicate that the flash can only go for 500 ms (half a second on the RX-51 (which is the N900). It doesn't say *why* it "Must be limited to 500 ms" though.

-Jeff
http://wiki.maemo.org/User:Jebba

Nice spot, jebba.

It looks like there may be an entirely different setting for the LEDs when used as a flash (up to 320 mA, so about 3.7V*0.32A=1.18W for up to half a second) versus when operated in torch mode (0.185W, same ballpark as estimated before). So, they would be overdriven briefly for the flash but operated at a safe level in torch mode. jakiman, can your setup measure light delivered in a short pulse? I'm curious what the actual flash output compared to the continuous mode output is.

>1W out of these LEDs would definitely be burnout territory...not to mention the battery drain! The question is, what is the actual drive current for each mode (those variables seem to be safety limits)?