Help needed: Building a QI charging TOH [answered]

asked 2015-08-07 14:22:29 +0200

V10lator
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What I did:

Buy a wireless transmitter (1500 mAh) from china.
Buy a wireless receiver (800-1000 mAh) also from china.

Now to the prototype: First I removed the sticker on the side facing the TOH: image description

Then I glued everything in: image description

Finally I added some pads made from aluminium foil: image description

First test with red cable facing to the middle, black the border: Phone crashed instantly. So I exchanged the cables. Second test: Charger tries to charge but phone doesn't do anything.

So before I do anything further I first want to know which cable has to face which side. I guess the second test was good (first short circuit) but the pads are bad (remember: Just a prototype) ?

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The question has been closed for the following reason "the question is answered, an answer was accepted" by V10lator
close date 2015-08-09 13:27:33.967028

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https://jolla.com/the-other-half-developer-kit/

There you will find details of the various pins on the Jolla, and what they're for.

r0kk3rz ( 2015-08-07 14:41:56 +0200 )edit

4

Do not use aluminium foil, usually it has an oxide layer and it is not a very good conductor. It adds resistance on both side, cable -> foil, then foil -> power pins.

Instead of aluminium foil use brass that You can solder the cable to.

Macilaci457 ( 2015-08-07 15:48:37 +0200 )edit

Aluminium will be good enough for testing though.

Giacomo Di Giacomo ( 2015-08-07 16:08:53 +0200 )edit

@Macilaci457 Again: proto, final design will be better (don't know how exactly but time will tell).

V10lator ( 2015-08-07 17:26:02 +0200 )edit

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answered 2015-08-07 14:44:26 +0200

chemist
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http://talk.maemo.org/

http://talk.maemo.org/showthread.php?t=92059 the pin further to the middle is 5V (red), the outer is GND (black), see this toh pinout (for your wires if the colour-coding is correct - black is usually GND-, red is usually plus+)

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This means that the first test (crash) was good. Did you check the charger provides 5 V dc?

Giacomo Di Giacomo ( 2015-08-07 15:13:57 +0200 )edit

Thanks guys, will check voltage and polarity next days.

V10lator ( 2015-08-07 15:32:21 +0200 )edit

0

answered 2015-08-09 13:22:08 +0200

This post is a wiki. Anyone with karma >75 is welcome to improve it.

updated 2015-08-09 13:26:05 +0200

V10lator
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Didn't get access to a multi and didn't want to wait more, so I bettered the pads and assembled a new prototype:

image description

Phone is charging through it while I'm writing this. :)

BTW: A little side question, just in case somebody know: As I tried to remove as much from the QI receiver casing as possible this black sticker you see there (below the electronics) cracked (some parts broke out completely). It isn't the sticker itself that broke but some substance attached to it. Without said sticker the receiver doesn't work at all (but it has no technical connection, the coil is below it. Looks like some kind of reflector to me but then I wonder why the substance is black and thick (shouldn't aluminium foil do the trick, too?)) so does anyone know what the substance is so I could get a replacement?

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Help needed: Building a QI charging TOH [answered]

The question has been closed for the following reason "the question is answered, an answer was accepted" by V10lator
close date 2015-08-09 13:27:33.967028

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Help needed: Building a QI charging TOH [answered]

The question has been closed for the following reason "the question is answered, an answer was accepted" by V10lator close date 2015-08-09 13:27:33.967028

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The question has been closed for the following reason "the question is answered, an answer was accepted" by V10lator
close date 2015-08-09 13:27:33.967028