Cloning a wireless power circuit!

[robjampar]

Im attempting clone a wireless charger for a project (Like this);

(http://www.aliexpress.com/item/5PCS-LOT-10mm-coil-wireless-charging-module-Receive-current-50-150mA-free-shipping/1841591643.html)

Right now i'm concentrating on creating the receiver, and just using the transmitter from Aliexpress to test with.

Im not entirely sure how the Chinese one works, Ive attempted to probe it and try and work out whats going on but its a bit difficult for me to reverse engineer.

Instead i've tried to recreate it how I thought it was working, and here is my first attempt,
I directly rectified the output from the recievers coils like this:

And the stepping down the voltage like this (V_IN is actually V_OUT):


Then i just pump the (expected) 5V output into a Li-ion charging IC. This works (sort of) but the coils have to be practically touching for it to deliver the 20mAH I set for the battery charger to work, and as soon as they are a mm further apart, the charging IC cuts out (I assume its the charger IC that cuts out at if it cant deliver the 20mAH).

Ive tried different values for C24 (the capacitor that is directly over the coils) to see if that has any effect, it does, but it only made things worse.

With the chinese one (it outputs 5V), I can get around 80mAH at around 1cm distance apart.

I would really appreciate any hints or pointers in the right direction on how to get it working more efficiently? - Or even if im doing anything stupid or totally wrong/there is a much better way!

Thanks to anyone that responds!

Ive attached a PDF that has all the helpful links ive found (Note: it also includes links for the Power TX, but I am not too worried about that for now)
These links are particulaty relevant:
http://diydrones.com/profiles/blogs/wireless-power-and-charging
http://www.sunrom.com/288

[PA0PBZ]

Ive tried different values for C24 (the capacitor that is directly over the coils) to see if that has any effect, it does, but it only made things worse.

Did you use the original coil from the chinese receiver and the same capacitor value? It is a resonant circuit and if it is off you will lose a lot of energy.