UPDATE: Tutorial now available!
Interested to know more about how YouTuber infinitemods got his HTC EVO 4G to work with the Palm Touchstone wireless charger?
I contacted him yesterday to ask if he might be interested in writing a tutorial for us here at G&E. I knew he was busy from a comment he left on YouTube, so I also asked some other quick questions that I hoped he could answer in the meantime.
He got back to me this morning and said that he would love to put together a tutorial for us as soon as he had "a few solid hours" to himself. To hold us over until then, he sent along the answers to my questions, all of which he typed on his EVO while on a lunch break.
How long did the mod take to complete?
The whole project took about a half hour, but it can be done in about 5-10 minutes.
Did you run into any problems while trying to get it to work?
There wasn't a whole lot of trial and error. I just used a multimeter to find the proper contacts on the board. Despite what most people think, the contacts from the induction coil DO NOT go directly to the battery contacts. You could damage the battery and possibly the phone like that.
Are there any drawbacks to the mod?
Neither of these bother me, but they might bother some people.
- The 4 magnets around the coil render any compass apps completely useless.
- The battery cover sticks up a little but as you saw in the YouTube video it's barely noticeable. I could probably make it fit better but I didn't want to modify the internal plastics just in case I ever have to return the phone.
How does it handle heat?
I've left the EVO on the Touchstone every night till morning and I haven't noticed a whole lot of heat. In fact, I felt more heat charging the phone using the micro USB cable or just through heavy use.
Anything else you'd like to share with us?
Thank you for your interest in my mod. To the best of my knowledge I'm the first person, if not the only person, to do this mod but I hope there are others out there trying it out for themselves. I will try to get a tutorial to you ASAP.
Wow this is great that you have gone this far with this cool find of mine thanks for contacting him i plan on trying this if he releases a tutorial.
Just to clarify, this only affects compass spa while on the charger, yes? I have trouble imagining why this would damage the magnets or something, but I just want to be sure.
I would imagine this affects the compass all the time. Induction charging uses magnets to do the wireless charging. I’m guessing that part of the coil you’re soldering in includes magnets, so they will be present all the time, hence consistently affecting the compass. If there is a compass in the Palm Pre, I am sure it is designed to be shielded from the induction magnets in some way.
All just guesses though
As I am about to receive my EVO on Tuesday to replace my Pre, I am SO ready for this guy’s awesome tutorial. I am curious tho if the magnet has a strong hold on the EVO. I have a Touchstone in my car and it hold’s on to my Pre even under very aggressive cornering.
This is all true…
I also have a touchstone in my car, which was the main reason I did the mod. The Evo hangs on fairly well but not as well as the Pre. The Pre has a slightly contoured back and the Evo has a flat back. As long as the touchstone is on a fairly level surface the Evo will hang on just fine under normal driving. My Evo & Touchstone stay in place on my center console even under very heavy acceleration in my ’85 300ZX.
Very nice!! Praises to you in advance
Can’t wait for the tutorial… I have already spread the work over at PPCGeeks… I’m sure there will be quite a few geekers interested in this as well…
Thanks in advance for sharing with us!!!
Induction charging does not use permanent magnets, it uses a coil in the base station through which an alternating current is passed. This creates a changing magnetic field that induces a current in the coil inside the phone. When the system is not charging there is no magnetic field present.
The permanent magnets that will mess up the compass are in the back of the phone and are there to hold the phone in the right place on the base station. If you can find a way to keep the phone in the correct position without using magnets (velcro?) then you won’t need them and your compass will work fine. Just make sure that the alignment is precise as I guess the efficiency of the induction process will depend strongly on this.
This system works just like the transformers you get in power supplies.
Reading: http://en.wikipedia.org/wiki/Wireless_energy_transfer
There are 4 very small magnets inside the backside of the Palm Pre. They are weak but they are magnetized. The dock has the larger and strong magnets.
I would think removing the magnets and replacing with unmagnetized iron disks would solve the compass problem.
You can remove the plastic ring from the touchstone and that allows the EVO to come a bit closer to the magnets in the touchstone. The magnets are really a single chrome plated piece of steel with 4 prongs that come out almost to the surface of the touchstone, but not quite to the surface, so even with the plastic ring removed, the metal parts do not touch the EVO’s battery cover. As for looks… It doesn’t necessarily look all that bad with the ring removed and the 4 magnets exposed, since they are symmetrically arranged and chrome plated. Personally the Palm logo bothers me more since it isn’t being used with a Palm any more.
There are no magnets in the phone (in the Touchstone battery cover)
The only magnets are in the touchstone base itself and it’s really just one magnet with a steel plate with 4 prongs that come out to the edges of the touchstone base in the plastic trim ring around the outside edge.
In the battery cover there is just a receiver coil and small regulator/conditioner circuit, and 4 iron plates. Not magnets, just plain iron/steel.
I have just peeled the receiver and iron plates from a Pre battery cover and transferred them to my EVO battery cover. That part was pretty easy and the end result is you hardly can tell the EVO has been modified at all unless you press on the battery cover and feel the littl lump with your fingers.
It sticks to the touchstone but only weakly compared to a Pre. It rocks a little and the iron plates are not allowed to come as close to the base as on a Pre due to a difference in the curvature of the different battery covers.
But it does hold well enough for indoor use. It would never hold in a car the way someone did for a Pre. Since I have 3 toushstones (bedroom, living room, office) it’s well worth it to make this work.
I have not yet done the wiring inside, just the simple physical/mechanical transfer of the guts. That was almost dead simple. You have to be a little careful physically to avoid damaging the components, and keep them all on the sticker instead of on the battery cover, but there is no rocket science involved. then just slap the whole thing on the inside of the EVO cover as if it were just an ordinary sticker. Piece of cake.
The wiring will surely be the tricky part. Hopefully you can just tap it on to the 5v from the usb. There are only two contacts on the output from the receiver, so no special data or sensor connections to worry about, just plain old power. Have to do a little checking with a multimeter to verify that the little circuit on the receiver coil includes it’s own diode to protect against backfeed so that when the usb port receives power from a regular charger, it doesn’t make it into the receiver circuit. If that’s true then this mod is really pretty simple conceptually and the only hard part is simply physical care dealing with small spaces and solder connections.
Why not snip off the four magnets on each corner of the coil and put a mod around the base of the touchstone to hold your EVO instead. Something that can snap on the touchstone (not your phone) just to keep your EVO from slipping off. You still get the desired effect without losing your compass.
I have finished duplicating this hack. It works indeed!
http://www.facebook.com/video/video.php?v=400059973239#!/video/video.php?v=400059973239
3 touchstones now not going to waste!!! Thanks infinitemods!
Differences:
I used 26AWG wrapping wire from radio shack, based on the fact that usb ports on pc’s are 5vdc 500mA and all the wall power usb chargers are 6v 1A or less (The Sprint one is 5v 850mA for instance, and the output of the receiver coil is 5.6vdc) so 30awg would be ok, barely, 28 would be fine, and 26 is more than beefy enough and results in a lot less voltage drop, yet is still very thin and fits between the case parts and the battery without straining anything.
I used the side of the usb port for the negative contact, right next to the positive connect point you illustrated. This makes neater wiring and avoids putting a bump in the flat surface that the case is supposed to screw down on to next to the screw hole you used.
And ran both wires laying parallel to each other never crossing one over the other just around and behind the vibrator motor right in to the battery compartment. I don’t have pics of the inside since I didn’t have my camera when I did that part.
http://www.facebook.com/video/video.php?v=400059973239#!/album.php?aid=175842&id=587058239&ref=pb
http://www.youtube.com/watch?v=AkeE45-xlPI
For the car, I’m going to do a neater version of this:
http://htcpedia.com/news/htc-evo-4g-car-kit-self-made.html
The EVO is too heavy and the magnets aren’t even close to strong enough to secure an EVO in a Staturn Sky Redline the way I drive it!
i have a question, would a coil from the palm pixie touchstone cover work? i just picked one up at radio shack for $6 as they are clearancing out all palm accessories. it looks a little different than my pre, but it works on the same touchstone base. i would imagine it would work. i plan on upgrading next month and this will be my first hack. i love the touchstone with my pre.
As I said in an earlier post, I’ve been trying to tap a touchstone for over a year now and the problem I ran into was the power saving feature employed by the base/receiver. The primary coil (in the base) is not energized continuously but only when the cover AND phone are on top of it. I bought a kit just for hacking it but again, I wasn’t able to trigger the charging mode with anything else but a Prē attached, which btw I don’t have.
Please tell me what’s that “positive” point in the photo – is it simply one of the USB contacts? So far I was convinced that the Prē sends some secret handshake signal to trigger charging but maybe it’s just my particular touchstone unit being defective
I can’t see the picture very well where the positive wire is soldered to. Is there a better picture or diagram out there of this?
I would think there would be a way to make the magnetic connection between the Evo and the touchstone a little stronger, any ideas…confirmed or otherwise?
Brian, can you take a close-up of the points you soldered to?
Here’s another pic of the Positive and Negative connection points inside the EVO.
The positive is simply soldered right to the end of the surface-mount component with the “T” on it. Tucked in so it’s really soldered to both the component and the circuit board pad the component is soldered to.
http://www.facebook.com/photo.php?pid=4670393&id=587058239
or
http://brian.aljex.com/gallery/v/Gadgets/EVO_Touchstone/
Do you think we can upgrade the 4 piece of magnets/piece of metal so it weould be beefer to stick on the touchstone.
the magnets are in the Touchstone and not back plate.
Induction Charging does not use magnets, it uses two coils of copper both the exact same size. It does cause a magnetic feild, but not made by magnets. the magnets are to auto position the phone when it is place on the charger…