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Nexus 7 Touchstone Mod (Part 7)
[ Start at Part 1: http://goo.gl/2gxd5 ]

(Note that this is just a roadblock on an alternative avenue I was looking at - the main avenue of using Palm touchstones is still viable, and now that my magnets have arrived I will be completing this soon).

Looks like the HP TouchPad charging stand is not compatible with the charging circuitry from the Palm phone touchstone back.  When the TouchPad coil is connected to the Palm phone charging circuitry and placed on a HP TouchPad charging stand, the voltage output varies wildly and never exceeds one volt.

Similarly, using a Palm phone coil and charging circuitry (which are designed to work with each other) on the HP TouchPad charging stand produces the same unusable result.

Using the TouchPad coil and the Palm phone charging circuitry on a Palm phone touchstone does work, but this is not a practical solution because it is no better than just using the original Palm phone coil with the Palm phone charging circuitry (in fact the voltage output is slightly less).

So it looks like we're not able to use a HP TouchPad charging stand for anything other than charging TouchPads.  For everything else (including the current work on wireless charging for the Nexus 7), I will need to use one or more Palm phone touchstones and Palm phone touchstone backs.  Luckily, those are cheap and in plentiful supply.

[ Continue at Part 8: http://goo.gl/EVhtJ ]

-- Rod
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Gary Parks's profile photoMark Milliman's profile photoRod Whitby's profile photoMassimiliano D'Ambrosio's profile photo
4 comments
 
My Touchpad just wiped it's beads of sweat and breathed a sigh of relief.
 
This mod will put my 2 phone backs and Touchstone to good use. Do you need an old Pre and batteries? 
 
Thanks for the offer - I have ample sufficiency of those things.
 
+Mike Clark The TouchPad back does not contain separate charging circuitry, only the coil (which is not useable for anything by itself).  The charging circuitry for anything after the Pre 2 is on the main circuit board for each device and is not separable for use in another device.
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