Epic 4G Touch-stone mod

darrenf

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Here's a tease for you Palm Pre converts. I'll be back with a write-up tomorrow:

E4GT-TS-mod1.png


;)

UPDATE: I posted the details here: http://forums.androidcentral.com/ep...c-4g-touch-stone-mod-details-lots-photos.html

-darren
 
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RamboDroid

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Here's a tease for you Palm Pre converts. I'll be back with a write-up tomorrow:

E4GT-TS-mod1.png


;)

-darren


My new Hero! Man, I was just looking at this touchstone thinking "wish I knew for sure where the charging points are in the housing would love that EVO mod on here"
And just like that here it is?

Looking forward to seeing how well it stays on the touchstone since there's no grippy back.
 

tdoom15

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Hows the charge speed?

I used the touchpad charger for the g s2 tonight, seemed to speed up the process quite a bit vs stock.
 

Flyboy1100

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If it is similar to the evo 4g touch stone mod, probably requires hackery I don't want to do. But
I really miss my touchstone, haven't had it for over a year now
Sent from my PC36100 using Tapatalk
 

Dixie

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Waiting hopefully!!! A few months ago, before I gave up on the Pre3 coming to Sprint, I bought 2 Touchstones for really cheap. :)
 

Flyboy1100

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Does the compass still work?I seem to remember when someone stood this for the evo it no longer worked due to the magnets

Sent from my PC36100 using Tapatalk
 

Honis#WP

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Damn, someone beat me to it. Damn you work! Always getting in the way of my fun.3

[edit] Reporting in on my attempt at this.

The coil, control board and 30 gauge wire all fit under the battery cover pretty comfortably. I ran the wires out to a USB jack that I took off some cheap USB cable I bought. It charges great, however, the touchscreen interprets touches incorrectly. I've narrowed down the cause to the magnetic field or maybe the metal capacitance of the natural magnets being literally 1mm to close to the screen. I narrowed it down to those by removing them and then placing it on the charger with no ill effects and attaching the magnets to a piece of paper and then manipulating the screen from the front. I'm leaning toward the magnetic field being the culprit and not the capacitance but it's still hard to tell. I'm writing this up as failed unless someone knows how to absorb the magnetic field of natural magnets. I want the phone to be held in place with more than the electromagnetic field between the coils.
 
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darrenf

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Thanks for your patience. I put together a full description of the mod, with photos, and tried to incorporate answers to the questions that were asked in this thread. I decided it was most appropriate to post it under the hacks and mods section. Here's a link:

http://forums.androidcentral.com/ep...c-4g-touch-stone-mod-details-lots-photos.html

I'll watch both threads so feel free to ask any questions that I didn't answer.

-darren
 
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darrenf

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The coil, control board and 30 gauge wire all fit under the battery cover pretty comfortably. I ran the wires out to a USB jack that I took off some cheap USB cable I bought. It charges great, however, the touchscreen interprets touches incorrectly. I've narrowed down the cause to the magnetic field or maybe the metal capacitance of the natural magnets being literally 1mm to close to the screen. I narrowed it down to those by removing them and then placing it on the charger with no ill effects and attaching the magnets to a piece of paper and then manipulating the screen from the front. I'm leaning toward the magnetic field being the culprit and not the capacitance but it's still hard to tell. I'm writing this up as failed unless someone knows how to absorb the magnetic field of natural magnets. I want the phone to be held in place with more than the electromagnetic field between the coils.

I'm impressed that you got the charging coil under the back. How much does it bulge? Does it stick OK to the Touchstone? I want to see a picture!

I've researched the digitizer problem and it's not caused by the magnets because the digitizer works fine when the phone is sitting on an unpowered Touchstone.

My next step was to remove the back from the phone, set the back on the Touchstone, and see how the phone would perform an inch away from the charging coils. Interestingly, it was every bit as erratic!

That leads me to think that the problem isn't in the coil at all, but in the current being passed to the phone. Others have experienced digitizer problems when charging off USB cables, so it might be a function of the voltage (5.5V measured at the contacts in the back) or amperage (1A into the Touchstone).

I'll do some more testing -- let me know what you find!

-darren
 

darrenf

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Honis,

Update: I took the power out of another touchstone back and piped it into a USB cable. With it connected to the phone there is no evidence of digitizer trouble. So much for the theory of it being current or voltage. :-/

I desoldered the wires from the back of the touchstone and extended them with some 12" test leads. When I get the phone more than 2" away from the back, the problems go away. That suggests that the trouble *is* caused by the charging coil or the charging circuit.

Interestingly, reassembled, the digitizer works fine for a second or two after being placed on the Touchstone, then the phone beeps to indicate that charging has begun and the digitizer gets flaky. I would expect that the Touchstone is always energized but I guess the EM field changes once the charging circuit allows current to flow into the phone. I still wonder if the trouble could be in the charging circuit itself.

With the back off, I rotated the back through all four orientations, moving the charging circuit to four different places, while resting the phone on top. The digitizer was affected in all four orientations.

:-/

BTW: Please post the details on your mod -- I would love to hear the differences between yours and mine!

-darren
 
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Honis#WP

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My setup is exactly like this guys:
Inductive cellphone charging without voiding warranty - Hack a Day

Not sure if there's a post limit before people can see links (like on PreCentral). If not google: Inductive cellphone charging without voiding warranty


After trying your tests (trying the phone touchscreen in different places while the coil is on the touchstone) and reading your attempts to lock it to a voltage problem I tried some things.

I put the magnets back in my setup and measured the voltage coming from the power leads (the exposed contacts). I measured a steady 5.6V. I then took the magnets out and measured. The reading obviously differed based on how centered the coil was on the touchstone but the readings were generally between 4.5V and 5.6V. I moved the coil to a point that was ~4.7V then plugged the phone in. It worked perfectly. This points to an over voltage to the phone as the culprit. I'll calculate a circuit tomorrow (probably) to try maintaining a lower voltage to the phone.


To answer your other questions:
If placed as high as possible in the back, the bulge isn't noticeable and the 2 wires coming out of the bottom are the only clue something has changed. If placed near the bottom, the lower latches are nearly impossible to latch and that makes it very noticeable and the back seems prone to pop off.

The phone holds on pretty weakly compared to my Pre. It does snap into place when the magnets are present. (I noticed in your writeup you call them metal stubs. Mine are magnets and the polarity is marked with a + sign which should face out from the phone).

Mistakes/gotchyas I've made/seen so far:
When reading pinouts online they are showing you the jack (female/phone) part. Mirror the pinouts to solder the plug (male) side.

Put magnetic stubs in backwards. Causes the phone to go cockeyed on the touchstone. The + sign etched in the magnet point away from the phone when everything is put together.

The D+ and D- pins need to be shorted on the USB plug (male) part. Just solder a wire between the pins (don't mistake it for the unused Pin 4). (Plug, not the jack which is the female part on the phone).
 

Honis#WP

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I don't have a case to try it with. If it's thin and not metal or a metal mesh it should work. In my setup the worst that would happen is needing to move the metal stubs/magnets between the case and the back. For yours I think you'd lose the solid snap in place but it would react more like the a Pre with no case.
 

roninlb

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Thanks for the reply. I ordered a TPU Case, so once my phone arrives, I'm going to try putting the touchstone guts in there and use the usb method to plug my phone in.
If it works, I'll post and let all you guys know.
 

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