Modded my cellular phone :)

mailint · Nov 2, 2007

I needed a flashlight in the smallest added space to my pockets so here is my new Rebellized cell. phone

Direct drived for a total 1750-1800 mA when battery is fully charged.

According to data sheet for Rebel 100, 900 mA for LED are 200 lumen for LED so I expect it to emit about/almost 400 lumen

greenlight · Nov 2, 2007

I can't call for help, we might need light later...

Manzerick · Nov 2, 2007

That looks like an HTC product is i'm not mistaken(6800 series)

Great work!!! i can't wait for these to be an out of the box solution

mailint · Nov 2, 2007

greenlight said:
I can't call for help, we might need light later...

Eheh but in facts it seems the opposite: from my first experiments the battery goes from 100% to 0% (for the phone) after "not many tens of seconds... of light" but when it's 0% while the phone turns off the light is still very powerful, let's say unnoticeably less powerful than when it's 100%!

"I can't use light for help, we might need phone later..."

mailint · Nov 2, 2007

Manzerick said:
That looks like an HTC product is i'm not mistaken(6800 series)

:thumbsup: it's an HTC Tytn

I have HTC Tytn, HTC Universal, HTC Athena and soon I'll probably buy a Tytn 2. This is why I opted to not use *adhesive* termal paste

Manzerick said:
Great work!!! i can't wait for these to be an out of the box solution

Me too..

The HTC top phones already have an integrated bright LED that acts as a light and as a flash for the camera but it's still far from being as bright as a Rebel 100/CR-E Q5/SSL P4...
I wanted to upgrade it too but I found it too hard to remove...

mchlwise · Nov 2, 2007

greenlight said:
I can't call for help, we might need light later...

(takesbreath) :crackup:

cmacclel · Nov 3, 2007

mailint;2210021 Direct drived for a total 1750-1800 mA when battery is fully charged. [/QUOTE said:
Without a LARGE heatsink the Rebel or any other LED will live a very short life at that current if used anymore than a couple seconds at a time.

Also the the higher the current the less efficient the LED is so 400 lumens is probably less than 300 lumens I would think.

Mac

TorchBoy · Nov 4, 2007

mailint said:
Direct drived for a total 1750-1800 mA when battery is fully charged.

Is that a good idea? I think it was DM51 who recently made a list of good practices for Li-ion that recommended sticking to <2C currents for Li-ion batteries.

mailint · Nov 4, 2007

cmacclel said:
Without a LARGE heatsink the Rebel or any other LED will live a very short life at that current if used anymore than a couple seconds at a time.

I usually start to feel significant heat after about 20-30 seconds... then I stop for 20-30 seconds... and I can restart...
I don't care of the LED file..

cmacclel said:
Also the the higher the current the less efficient the LED is so 400 lumens is probably less than 300 lumens I would think.

This inefficiency is already considered in my 400 lumens calculus. In fact the data sheet indicates 1x 100 lumen at 350mA and the graphic curve reaches 2x lumens at about 900mA (instead of 700mA that is 2x 350mA).
My assumptions are:
350mA = 100 lumens
900mA = 2x 350mA lumens = 200 lumens
2 x 900mA = 2x 200 lumens = 400 lumens

I think that the most significant inefficiency that I'm not considering is the thermal one but to be sincere I don't perceive with my eyes differences in brightness between when it's cold and when it's hot...

mailint · Nov 4, 2007

TorchBoy said:
Is that a good idea? I think it was DM51 who recently made a list of good practices for Li-ion that recommended sticking to <2C currents for Li-ion batteries.

Yes, I applied that recommendation

The battery is 1350mA. 2C = 2700mA.
Anyway I believe that that recommendation refers to continuous discharge while I use it for fast bursts even because of the heat the LEDs produces..

2xTrinity · Nov 4, 2007

Eheh but in facts it seems the opposite: from my first experiments the battery goes from 100% to 0% (for the phone) after "not many tens of seconds... of light" but when it's 0% while the phone turns off the light is still very powerful, let's say unnoticeably less powerful than when it's 100%!

Yeah, most cell phones shut off when there is still a fairly significant amount of reserve power left on the battery -- I beleive that is done so that the cell is not overdischagerd from the quiescent current if the phone is left sitting around.

mailint · Nov 4, 2007

2xTrinity said:
Yeah, most cell phones shut off when there is still a fairly significant amount of reserve power left on the battery -- I beleive that is done so that the cell is not overdischagerd from the quiescent current if the phone is left sitting around.

Interesting theory...

nitnapz · Nov 4, 2007

this would provide an awesome use for taking pictures with the HTC's 2mp camera. like one second bursts or even video. the onboard light aint that good.

Illum · Nov 4, 2007

thats alot of current

oo:
what did you use for the heatsink? the cellphone case?

mailint · Nov 4, 2007

nitnapz said:
this would provide an awesome use for taking pictures with the HTC's 2mp camera. like one second bursts or even video. the onboard light aint that good.

I thought to it but there's a problem: the camera is on the back and putting the LEDs on the back of the phone is not confortable since it's the side that I use to lay the phone to the table. It would also ruin the glass of the LEDs with time...
Furthermore I don't know how much it can be safe for the 1350mAh Li-Ion battery to record video while LEDs takes near to 1800mA alone.

Illum_the_nation said:
thats alot of current oo:
what did you use for the heatsink? the cellphone case?

Yes, the cellphone case. I attached the LEDs to the phone using Arctic Silver 5 (not adhesive) thermal paste and a 5cm Scotch that covers the soldered contacts and half of the mini PCB of the Rebels and helps to keep them attached.
Heat and battery life for the phone (not for the light) are the most significant limit of this setup.

eyeeatingfish · Nov 5, 2007

So you going to show us how you wired it in?

mailint · Nov 6, 2007

eyeeatingfish said:
So you going to show us how you wired it in?

Sure!
I used normal electrical wires, a little power switch, heat shrink tube, soldering.
BTW I forgot to mention Super Attack to attach the reflector.

My next steps will be:

- to substitute the wires with thinner, possibly flat, wires so that they can exit from the battery without causing curvature to the battery cover
- to give it variable intensity (I still need to find a little variable resistance that handles 2A-3V)
- to add a slide-out flat reflector (I'm currently investigating the most reflective thin/flexible materials, including metallized Mylar and Anolux Miro-Silver...)

Haz · Nov 6, 2007

Nice work you have done, i've always wanted a phone with a powerful flashlight in one.

eyeeatingfish · Nov 6, 2007

So the process is relatively simple? wires to the battery, a switch and a couple of LEDs. Im guessing if there was only one LED there would be too much power to the LED from the battery?

You could always just drill the case to fit the wires.

I am now wishing to do this to my phone too.

mailint · Nov 6, 2007

Haz said:
Nice work you have done, i've always wanted a phone with a powerful flashlight in one.

Feel free to copy the idea and to improve it!

Modded my cellular phone :)

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