Color-coded clock! by full color OLED

Halloween clock! All the source is released at github, and actual operation can be found in the following movie.... Have fun!

Enclosure (case) was made by 3D printer and putting into it..

Embedded battery (LiPo) charging is quite easy. Just putting it on Qi charging unit, done! During charging, RED LED turns on, and

After full charge, it turns to white. Very bright!

Surely it works,

BUT the big size of Qi receiver is not acceptable at all. In the previous log, I confirmed its structure, and this time I make it smaller by coil rewinding!

I just remember that I am teaching electromagnetic and in the course I always say "Every electromagnetic effect can, and should be analysed, designed by theory! "... I forget it a few minutes. As in picture, Qi coil is rewinded with smaller dimension than original to fit it to back of "colour coded clock". I was completely not sure that such a random and irresponsible coil would work appropriately, but it produces 5V, as you see!!!

And the modified coil is re-assembed and put inside adhesive sheet. Very small!

Finally I put it back of the clock and confirmed LiPo battery is charging correctly!!

Qi is an wireless power transfer system, and according to wikipedia, OOK 2kbps communication between charging station and receiver is established in order to detect non-receiver object on charging station. So I guess some circuit inside it, and dis-assembled...

This is the inside of Qi-receiver. These two sides are simply attached by adhesive thin tape. The grey part of left part is some thin magnetic material, which will have high permeability to produce high magnetic flux density. The right side (circuit side) has a coil and circuitry.

The coil is wounded by 5-in-one (not bifilar but pentafilar ?) 5-lines are consisting this coil so the number of turn is not so much. During operation, this part produces some temperature increase. This thin coil is simply fixed by adhesive sheet, and the structure is simple so may be I would make some different form.

This summer, during stay in NY, I bought Qi charging circuit and receiver at tinkersphere, but until today I did not touch it. This morning, I briefly check its performance and understand how it is useful and easy to handle. I quickly order at amazon for charging station and receiver patch for some smartphone, and.. excellent Amazon.co.jp delivers my afternoon order in the same evening...! (two patches and station are less than 1000JPY..!)

This is the charging receiver. Before wiring it with my circuit, I check basic specification.

On the top of charing unit, it provides around 5V. Wonderful!

Moreover, electrodes are isolated, means it can be inserted parallel to USB 5V! Just wiring + and - to USB 5V and GND, leading...

Now my prototype "colour coded" watch has a wireless Qi battery charing function!