- 01-17-2013, 05:47 PM #1
I upgraded to the 822 about a month ago and really like it. Its smooth, fast and responsive a welcomed change from my aging Palm Pre Plus. The only thing I miss is using my touchstone charger. I can't bring myself to invest in new charging plates and wireless back.Looking at the 822 wireless back,it has 4 contacts instead of 2 like the pre. I would like to try and do a mod with my old pre back, but does anyone know why there are 4 on the nokia and what their polarities? The nokia battery has a positive, negative and neutral. Anyone know the details to the 4 contacts or know where to find them?
- 01-19-2013, 10:04 PM #2
I miss my Touchstone too, and I have 3 of them that are now relics, but I decided it's better to bite the bullet and get the Nokia charging back and stand. I now have two stands (one for home, one for office) for one phone. The good news is that the charging works very well, more reliably than the Touchstone used to (if the Pre wasn't positioned just so, the phone would sometimes cycle on and off charge, beeping every time unless I turned off the volume). The bad news is that the screen on the Nokia doesn't stay lighted when it's on the charger the way the Pre did, so I have to hit the power button to check if there's any news. I'm hoping that there might be a software fix that would make that an option.
- 01-21-2013, 08:05 PM #5
Explains why it doesn't work. Basically touchstone is proprietary wireless charging tech. Qi is a universal standard.
- 01-23-2013, 08:06 PM #6
What would be interesting is to see if the coils from a Touchstone phone back could be installed in a Lumia 822 back and allow the phone to 1) stick to a Touchstone, and 2) charge off the Touchstone. I believe the difference in the standards just deals with the coils. Might require a wiring mod to make it work, but someone who has a Palm phone and an 822 could check and see if the 2 charging contacts of the Touchstone back line up with the charging contacts on the 822 (I don't believe all 4 contacts are to charge, but I'm not sure - if anyone has the tech specs on this stuff, I could tell you pretty quickly).
- 01-30-2013, 08:34 AM #7
The tech spec sheet is what I can't seem to find. I don't even know where to get one. I tried using a multimeter to figure out what the four prongs do, but I don't think I was able to figure anything out. I ordered some conductive copper tape to see if I can do some sort of mod with the coil from my pre. I'll have to see if I can get some time this weekend to play with it.
- 02-01-2013, 10:09 PM #8
Looking at the pictures of the phone, it looks like there are 4 contacts on one side and a pair on the other. The wireless charging cover appears to mate with the single pair on the left side of the phone when looking at it's battery compartment (right side of phone when looking at display), which means the 4 contacts on the other are probably for something else, such as NFC or some factory use. It looks like a Touchstone wireless receiving coil from a Pixi would actually be the better coil to use as the contacts would be roughly near, and wide enough to put some contact foil or wire coming in from the contacts. It's also thinner than the one from the Pre covers. I would imagine that the Touchstone coils will be the correct winding ratio, assuming Qi and Touchstone charge with the same rough voltages/currents (I would guess yes, as I would assume they would present a charging source, to the device, that looks the same as one coming off a USB charger - would simplify the design as there would be no need for further regulation/conversion).
If a Touchstone coil mod works on these phones, that would be great news for those of us running around with a bunch of Touchstones, especially since I would be able to plunk the phone down onto the one in my car and it would stay there due to the magnets in the coil set for Touchstone backs. I won't be able to find out until later in March, so good luck to anyone willing to try. If it works...please share.
- 02-08-2013, 12:57 PM #11
Well I have been playing with trying the mod and trying to find out the polarity of the four contacts. Here are my voltage results using a multimeter with the phone turned on. The (+) and (-) are from the multimeter and I labeled them based on where I placed the (+) lead from the multimeter. Their position also correlates to contacts/leads of the phone (top-down):
(-) = -0.0
(-) = -1.7
(-) = -0.0
(-) = -0.0
(-) = -1.8
(-) = -0.0
(-) = 1.7
(-) = 1.7
(-) = 1.7
(-) = -0.0
(-) = -0.0
(-) = -1.8
Does anyone know about electricity and can help understand these results?
- 02-12-2013, 06:17 PM #12
Those voltages aren't standard for a Lith-Ion. As I mentioned above, I believe those 4 contacts are not the wireless contacts. I believe (from screen shots of the back of the phone and the wireless charging backs) that there are 2 contacts on the opposite side of the phone that are the ones used for the wireless charging. Take a look at your phone back again and see if there is a set of 2 contacts across the back from the 4 contacts.
I can't really tell anything from the measurements you did make, though, being a test engineer, I can tell you that a lot of dense devices, such as DSP's, CPU's, and FPGA's use 1.8V for their supply voltages (the other common one is 3.3V). Typically, the Li battery will supply somewhere between 3.4-4VDC, which will then be regulated to 3.3V and 1.8V to power the various devices on the phone's PCB, as well as driving the display and radios.
- 02-12-2013, 09:24 PM #13
Last edited by wingman7000; 02-12-2013 at 10:03 PM.
- 02-14-2013, 08:43 PM #14
Well, I'll be able to get mine in a little over a month. I can experiment then. At this point, my best guess is the middle two contacts. Direction shouldn't matter since coils transfer power by alternating the direction of current flow back and forth at whatever frequency they are designed to do it at (I would imagine the TouchStone and Qi chargers are 60Hz). You could probably put a touchstone back onto a touchstone and tape a wire to each contact(EDIT: May be best to wire first...then place on touchstone...for safety sake!), then touch or tape the wires to the middle two contacts on the phone and see if it starts charging. The coils in the touchstone backs are designed to match up to the coils in the touchstones, as the Qi chargers are similarly matched. So it should provide proper power for charging the batter at that point.
If you have, or can get, one of the 822 wireless charger backs, you can place it on a touchstone and see which two contacts are generating current, which would make this less of a guess. I can't really do more until I have a phone in hand.
- 03-05-2013, 08:43 PM #15
After messing around, this is what I know. The Touchstone backs put out a 5VDC charge, probably to match USB charging at around 500mA, probably around 50% effeciency. The spec that I can get without signing up, shows Qi is 5W at up to 70% efficiency. So that would put the numbers in the same ballpark of 5VDC and around 700mA max, within the USB spec, and likely closer to 500mA regulated. I would guess that the differences between the two specs is primarily the turns ratio, which is why placing a Lumia, w/charging back, on a Touchstone will indicate charging, but probably doesn't pull enough current to actually charge. I'm betting a Touchstone back coil will work with the Lumia, but the question is what contacts need to be hooked up to.
The Lumia has 4 contacts, instead of two, for the wireless charging. I suspect that the "extra" contacts are for either 1) current (2 smaller wires to handle the current of one larger one) or 2) for feedback for regulators. They could also be dummies, or have some other communication use for communicating with charging bases like the new HP stuff was going to do with the new version of Touchstones. What I would need is to see what the voltages are, pin to pin, for the 4 contacts of a Qi wireless Lumia back when it is placed on a Qi wireless charging base, sans the phone. This way, it would be easy to see what voltages it supplies - the rest is easy. So if anyone has one, and wants to put the information out there, I'll use it, and verify it, with my Lumia 822 I got off ebay (I'm still getting a free one from VZW at the end of the month, so I can experiment a little). I've also found out that the backs for the Pre's have 4 metal discs that are use to hold the phones to the magnets on the Touchstones. The 4 discs are place to where 4 corners where they would orient around the Touchstone, like a circle, allowing for the centering and multiple orientations. You need more than these 4 discs with the white Lumia because of the slickness of the back. I suspect the matte finishes will stay on, and I suspect this is why all of the Touchstone backs were matte. If not, simply adding 4 more discs, in alignment with the circular magnet of the Touchstone, will likely get it done, slick back or not.
- 04-19-2013, 10:28 PM #17
I don't have a wireless charging back for my 822, or I would have it figured out already. I highly suspect it's a two wire per pole charging system to handle current and/or kelvin feedback. If someone has a wireless charger and DMM and can tell me the voltages, contact to contact, I can figure it out. The biggest problem is really going to be getting the phones to stay on the Touchstone. I added the 4 small metal discs from the extra Pre+ touchstone charging back I had to the inside of the batter cover. The phone will center on the touchstone and stay there, but barely. Need a metal ring to really get the magnetic seal to hold the phone. Of course, a matte back would work better than the glossy cover I have.
- 04-30-2013, 10:12 AM #18
Re: getting the phone to stay on the Touchstone, people have used these magnets (K&J Magnetics - Products) when modding the Galaxy S3. I ordered a Touchstone back for my S3 (Amazon.com: Wireless Charging Back Cover/Back Door ONLY for Samsung Galaxy S3 I9300 , Marble White; A Separate Palm Touchstone Charging Set (including Dock, Adapter and USB Cable) is Needed!: Cell Phones & Accessories) and it is soft touch. That plus the magnets they added hold it to the touchstone nicely.
- 04-30-2013, 10:14 AM #19
Here's the thread over on AC re: Touchstone mod for Galaxy S3: http://forums.androidcentral.com/t-g...ne-mod-s3.html. Has some detail about the magnets and taping the charging coils down, etc. I imagine some of that could translate to the 822.
- 04-30-2013, 12:26 PM #20
Use magnets with caution - there have been cases of strong magnets damaging the compass in the phone.
I personally use a case that has a magnetic closure, and haven't had any problems that I've noticed (unless that's why Photosynth always wants to calibrate before I can use it), but that doesn't mean it can't happen.
- 05-01-2013, 09:21 AM #21
I plan to pull the coils off a Pixi and see what I can do with the 822.
- 05-22-2013, 05:02 AM #22
Sorry I haven't responded to this thread (been gazing at the 928 thread since I still have my upgrade available too me). The thread in question involves phones that use 2 contacts, like the Pre and Pixi, to wirelessly charge. The Lumia uses 4. If they simply are pairs for current handling, no problem, but I still need to know which ones pair together. The magnets link is good. Don't know if I'm going to get this done or not. I need a wireless shell and I'm not going to buy one if I switch to the 928.
- 05-23-2013, 05:55 AM #23
Unfortunately I pretty much gave up on converting my palm charger to the 822. It's been too busy for me to be able to sit down and play with it anymore and it was driving me crazy that it wasn't working for with all the combos I tried.
- 05-23-2013, 08:18 PM #24
Oh well. If anyone get's me the voltages from the wireless back itself (not the phone) so I can figure the pin out, I can at least guide people on how to do it. Until then, I don't see this happening anytime soon.
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