# opencoil-paracity: electronics



![picture](https://git.vvvvvvaria.org/then/opencoil-paracity/raw/branch/master/electronics/esp-wireless-charging-pcb/pcb-ass.jpg)

*Assembled pcb*

### Bill of Materials 

* PCB: Send the gerbers from this repo to your fab of choice.
* ESP12F: Widely available.
* AM1117 3.3v Regulator: Widely available.
* QI compatible wireless charging coil delivering 5v and > [500 mA](https://docs.ai-thinker.com/_media/esp8266/docs/esp-12f_product_specification_en.pdf): For example [this](https://aliexpress.com/item/4001154059743.html), search keywords: "pcba receiver module qi". Alternatively you could repurpose coils advertised to convert non-QI phones to wireless charging, such as [these](https://www.pearl.de/mtrkw-9811-qi-kompatible-receiver-pads.shtml)*. 

* **NOTE**: Be aware that these 'converter pads' could contain additional circuitry that condition the output for use with specific mobile phones (the pearl.de ones do). Below is a guide to modify the 'pearl' coils to deliver maximum voltage (5v)constantly, instead of switching to low power, 2.5v output when not enough/too much current is drawn.


### Modding Coils/pads

If you have soldered all components together and your ESP12f won't boot, you might have to modifiy your charging coil+circuit a bit. To make sure it's the coild, measure the output of the coils electronics on the + and - (gnd) terminals. If your multimeter reads ~2.5 volts you need to modify the circuit. (Disclaimer: the exact details on how this circuit works are yet unclear, comparing to a working coil revealed several differences in the electronics, matching them up made the non working coil output the needed 5v). 

##### Step 1

Take off the follwing chips indicated by the following silkscreen printing:
* Q3 (chip markings: p7)
* Q4 (chip markings: wsc7)

A hot air reworking station + tweezers will make quick work of that (settings: 1 second on 320deg, modertate airflow). Without hotair you could try a soldering iron or fine wirecutters to simply cut away the chips. The flexible PCB is very fragile though.

##### Step 2

With both chips removed, you have to bridge two of the three (now) bare connections of the transitor Q4. I could not find a datasheet on this transitor so please refer to the photo's to see which pins.