[darrenf]

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





UPDATE: I posted the details here: Epic 4G Touch-stone mod details [LOTS of photos]

-darren

[jazbojenkins]

wow!

[youngjediboy]

Hell yeah! Please say you'll be offering your mod services. I'd pay!

[RamboDroid]

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





-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.

[JayWill]

Oh man. That's like 10 different forms of awesome!

[tdoom15]

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.

[Mikest]

bookmarking this thread. Please let it be true (and easy)

[Croathlete]

YES YES YES!

Sent from my SPH-D710 using Tapatalk

[Flyboy1100]

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]

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

[Flyboy1100]

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

[milominderbinde]

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

That was the problem that everyone had when they put the rare earth magnets on the back of the Android phones...

[Honis#WP]

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.

[darrenf]

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:

Epic 4G Touch-stone mod details [LOTS of photos]

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

-darren

[darrenf]

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]

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

[Honis#WP]

My setup is exactly like this guys:


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).

[roninlb]

Honis,
Do you know if the touchstone still works if you put the phone in a case?
Thanks.

[Honis#WP]

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]

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.

[Honis#WP]

Well, to try and get my mod working I introduced about a 1ohm resistance between VCC off the coil and the USB port. The max amperage from the Samsung AC/DC adapter is 1Amp so it dropped the voltage about 1V to roughly 4.6Volts into the phone. I measured to confirm the drop. I still got a wonky touch screen.

Doing some retesting at this lower voltage, the digitizer problem is most assuredly from the static magnetic fields coming from the TouchStone. Removing the stubs/magnets from around the coil greatly reduces the range of the effect. When they're in place they are extending the magnetic field which makes it all that much closer to the screen/digitizer.

These magnetic fields are not absorbed by a Faraday cage because they are static (think bar magnet and metal filings). The magnetic field coming off the coil is blocked because it oscillating magnetic fields (think of a sine wave) which are blocked by Faraday cages (the metal tetris piece is providing the blocking in 1 direction).


Knowing all of that I'm putting a close on my project. I don't want to take a TouchStone apart to remove the alignment magnets because there will only be friction from weight holding it in place and I'm thinking there will be more forgiving devices than my GS2 that this can be added too. (PSP, PS3 controllers, a DS, etc.)

[darrenf]

-Roninlb, as Honis said, as long as your case isn't too thick and doesn't have metal in it you should be fine. If the back has some grip that will help it stick to the Touchstone. The Pixi back is a good bit thicker than the Pre's but still works. Please report back on your progress!

-Honis,

I have a couple more data points to evaluate should you decide to continue research with me on the digitizer issue. The digitizer works fine when the phone is on the touchstone in my car, with an audio plug connected, playing podcasts. The improvement isn't caused strictly by the connection of the headphone cable -- I have to have loaded the CPU a little. In a separate test, the digitizer works fine when the charging cycle is complete or nearly complete (>~98%), even at idle.

My hypothesis is this:

When nearing a full charge, the phone starts to trickle charge, which reduces the current through the charging coil (similar to the effect you got with the phone off-center of the Touchstone). It makes sense that this would lead to a weaker RF field around the coil which we are assuming is related to the problem.

What complicates this is that with the phone charging at 50%, the digitizers work if the CPU is loaded. I suggest two possibilities:

1. Higher heat in the phone causes the charging circuit to slow the charge, or

2. The increased load means that a percentage (more than half in this test) of the charging current is powering the phone, which means that only half as much current is going into the charging of the battery.

Theory 1 makes good sense but didn't correlate 100% with my observations. #2 does, but means that the problem is a combination of high-current through the *charging circuit built into the E4GT* in the presence of the charging coils (because at a distance from the coils the effect goes away).

This is all observational from one long drive home. I'll do some testing on the bench to see if I can narrow the cause.

One other issue has me puzzled and it's not related to the digitizer but rather to the studs/magnets on the phone that center it on the Touchstone. I have eight charging backs, some old and some unopened. Most are from Pres and one is from a Pixi. I picked a sample of four of them to test out tonight and not one of them has magnets in those four points around the coil.

I pulled a stud out from each and tested it with the lightest ferrous things I could find, including metal filings from sawing on a piece of iron pipe, and got no attraction to either side of the stud. They are marked with a plus or X so it makes sense that they would be polarized, but unlike in your test I'm able to position them on the touchstone and then flip them over and they snap back to the *exact* same place. Also, all of mine were manufactured with the plus towards the *inside* of the phone and I think you said that yours didn't work in that arrangement.

Particularly perplexing to me is the video you linked to of the external touchstone mod. In that example, he definitely has magnets -- they all but jump out of his hand and stick to the phone (which, by the way, I would not have expected to be made of a ferrous metal).

All I can guess is that the design of these studs was changed at some point along the way. Perhaps magnets were used in some models to get a better grip on the Touchstone. Very odd. Not really significant, but odd.

-darren

[darrenf]

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.

Charging speed seems on par with a 1A charger wired straight in. There should be some loss because induction coils aren't known for efficiency, but in my tests with my Touchstone modded Nexus S 4G, I found that I got more or less the same charging rate with the touchstone as when I removed the 1A 5V supply line from the Touchstone and plugged it straight into the charging port on the phone. Being a Nexus S 4G, of course, the charging rate was terrible in both cases. :-)

Interestingly, tonight I charged my E4GT for a bit with an external battery pack that said it put out 1.5A. The phone went from 2% to 50% in 70 minutes. Nice! It's good to know that it will charge that fast in a pinch if I have to bring it back from the dead!

-darren

[Honis#WP]

-Honis,

I have a couple more data points to evaluate should you decide to continue research with me on the digitizer issue. The digitizer works fine when the phone is on the touchstone in my car, with an audio plug connected, playing podcasts. The improvement isn't caused strictly by the connection of the headphone cable -- I have to have loaded the CPU a little. In a separate test, the digitizer works fine when the charging cycle is complete or nearly complete (>~98%), even at idle.

My hypothesis is this:

When nearing a full charge, the phone starts to trickle charge, which reduces the current through the charging coil (similar to the effect you got with the phone off-center of the Touchstone). It makes sense that this would lead to a weaker RF field around the coil which we are assuming is related to the problem.

What complicates this is that with the phone charging at 50%, the digitizers work if the CPU is loaded. I suggest two possibilities:

1. Higher heat in the phone causes the charging circuit to slow the charge, or

2. The increased load means that a percentage (more than half in this test) of the charging current is powering the phone, which means that only half as much current is going into the charging of the battery.

Theory 1 makes good sense but didn't correlate 100% with my observations. #2 does, but means that the problem is a combination of high-current through the *charging circuit built into the E4GT* in the presence of the charging coils (because at a distance from the coils the effect goes away).

This is all observational from one long drive home. I'll do some testing on the bench to see if I can narrow the cause.

One other issue has me puzzled and it's not related to the digitizer but rather to the studs/magnets on the phone that center it on the Touchstone. I have eight charging backs, some old and some unopened. Most are from Pres and one is from a Pixi. I picked a sample of four of them to test out tonight and not one of them has magnets in those four points around the coil.

I pulled a stud out from each and tested it with the lightest ferrous things I could find, including metal filings from sawing on a piece of iron pipe, and got no attraction to either side of the stud. They are marked with a plus or X so it makes sense that they would be polarized, but unlike in your test I'm able to position them on the touchstone and then flip them over and they snap back to the *exact* same place. Also, all of mine were manufactured with the plus towards the *inside* of the phone and I think you said that yours didn't work in that arrangement.

Particularly perplexing to me is the video you linked to of the external touchstone mod. In that example, he definitely has magnets -- they all but jump out of his hand and stick to the phone (which, by the way, I would not have expected to be made of a ferrous metal).

All I can guess is that the design of these studs was changed at some point along the way. Perhaps magnets were used in some models to get a better grip on the Touchstone. Very odd. Not really significant, but odd.

-darren

That doesn't make much sense to me. The device will only draw the current required to Charge and run the phone. Redirecting the current to the rest of the phone shouldn't change the input current since it's being redirected and not reduced. I would even go so far to say that it's drawing more current when loaded down and charging.

It's nearly impossible to get a resistance reading while charging so I'll try and find my Amp-meter and measure what it's actually drawing while charging tonight.


I've been thinking about the metal stubs/magnets and what you've been saying about them. The ones I'm using were from a well used back so it's possible they were magnetized from use.

[morrison0880]

Have you thought about trying the mod using a sort of case instead of vinyl stickers? Something simple like this?