# 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


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## greenlight (Nov 2, 2007)

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


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## 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


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## 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..."


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## 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...


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## mchlwise (Nov 2, 2007)

greenlight said:


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



 (takesbreath)


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## 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.
> 
> ...


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## 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.


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## 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...


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## 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..


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## 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.


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## 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...


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## 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.


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## Illum (Nov 4, 2007)

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


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## 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.


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## eyeeatingfish (Nov 5, 2007)

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


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## 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...)


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## Haz (Nov 6, 2007)

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


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## 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.


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## 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!


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## mailint (Nov 6, 2007)

eyeeatingfish said:


> 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.


 
Yes, it's relatively simple.
I tried with a single Rebel and it took about 1.2A alone. Since data sheet of the Rebel recommends max 1A and since I want moooooore light and less heat I opted for 2.
Furthermore when I attached a reflector to one of them and I found a lovely 3 intensity levels beamshot as a result of the setup, I confirmed to myself that that is an optimal configuration.

In my next trials I think I'm going to experiment with even more Rebels. I want to obtain the most out of the given battery.


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## eyeeatingfish (Nov 7, 2007)

I want to try working with rebels, but they are so tiny, i dont know if i can soder that well...


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## Illum (Nov 7, 2007)

Haz said:


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



I've always wanted a flashlight with a cellphone option....maybe imitating whats done here might get me a fully functional Mag cellphone I can call for help when the batteries die


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## mailint (Nov 8, 2007)

eyeeatingfish said:


> I want to try working with rebels, but they are so tiny, i dont know if i can soder that well...


 
Nooo you don't have to solder the Rebels directly... 

I bought/used Rebels on 1cmx1cm PCB:







For my bigger cellular phone, an HTC Universal, that has a double capacity battery of 3200mAh and a triple capacity battery of 4800mAh, I will try with a series of 6 Rebels like this:







I would use the rear of the screen, covered by a mirrored film (see my other thread about the best materials: https://www.candlepowerforums.com/posts/2211105), as reflector, concentrating the vertical angle from 180° to 90°, more useful for example for illuminating the floor while you're walking.
I created a picture of the concept:


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## eyeeatingfish (Nov 8, 2007)

Where did you purchase the LEDs?


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## Fallingwater (Nov 8, 2007)

Two things:
1) put some hot melt glue on the reflector to keep it in place. Cyanoacrilate (superglue, super attak) is not too good to glue surfaces that aren't perfectly flush with each other. It also has very good resistance to pulling, but poor resistance to torsion (or shear stress). This means that you're unlikely to be able to pull the reflector off by just tugging on it, but if you push sideways, or if the phone snags something and the reflector is pulled, it'll come off with surprisingly little effort.
Melt glue, while not as strong as superglue, is softer when cured, which gives it much more resistance to torsion. It also can be applied in generous blobs without problems. Apply too much cyanoacrilate and it'll flow off and not cure well.
2) please, please put some resistance in series with that poor LED.


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## TorchBoy (Nov 8, 2007)

Fallingwater said:


> Melt glue, while not as strong as superglue, is softer when cured, ...


... and even softer when it heats up.


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## Fallingwater (Nov 8, 2007)

...oh.
Right.
Heh heh.


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## johnny13oi (Nov 8, 2007)

mailint said:


> :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
> 
> 
> 
> ...



Man those are some extremely nice cell phones. Been looking for a Universal but they're so expensive. And that Tytn 2 is so awesome. If you're gonna get it .. as a heads up the ATT 8925 (Tilt) is the same as the Tytn 2 and can be purchased for about 450 on ebay. Too much for my blood though.


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## mailint (Nov 17, 2007)

Fallingwater said:


> Two things:
> 1) put some hot melt glue on the reflector to keep it in place. Cyanoacrilate (superglue, super attak) is not too good to glue surfaces that aren't perfectly flush with each other. It also has very good resistance to pulling, but poor resistance to torsion (or shear stress). This means that you're unlikely to be able to pull the reflector off by just tugging on it, but if you push sideways, or if the phone snags something and the reflector is pulled, it'll come off with surprisingly little effort.
> Melt glue, while not as strong as superglue, is softer when cured, which gives it much more resistance to torsion. It also can be applied in generous blobs without problems. Apply too much cyanoacrilate and it'll flow off and not cure well.


 
I totally agree! In fact the reflector detached two times during last two months...
Another reason I want to change glue - or to renounce to the reflector - is that this Super Attak starts to make a bad smell and some smoke after about 20-30 seconds of runtime.



Fallingwater said:


> 2) please, please put some resistance in series with that poor LED.


 
I need a good reason before using resistances. Till now I' happy with my cell. torch, using it only in rare/fast circumstances.

By the way I'm from north-Italy too


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## mailint (Nov 17, 2007)

eyeeatingfish said:


> Where did you purchase the LEDs?


 
from ledtech.de


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## mailint (Nov 17, 2007)

johnny13oi said:


> Man those are some extremely nice cell phones.


 
Yes, I'm convinced that these HTC phones, expecially the Tytn II, are the *current* market best for technology.


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