Repo for non destructive e-scooter intervention materials
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then 0fb2d4c065 added coil pins 2 years ago
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esp-wireless-charging-v2 added coil pins 2 years ago
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README.md

opencoil-paracity: electronics

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Assembled pcb v1

As of 2022 there is a PCB version 2 with extra breakout gpio pins, schematic here

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Assembled pcb v2

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: For example this, search keywords: "pcba receiver module qi". Alternatively you could repurpose 'adaptor coils' advertised to convert non-QI phones to wireless charging, such as these*.

NOTE: Be aware that these 'adaptor coils' 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 'adaptor coils'

If you have soldered all components together and your ESP12f won't boot, you might have to modify your charging coil+circuit a bit. To make sure it's the coil, measure the output of the coil's 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

You need to desolder two IC's/ chips following the (visual) guide below. The electronics and coil are sandwiched between two layers of foil. To peel the foil away look for an opening near the lightning connector.

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You are then left over with the bare coil and flexible pcb. Here I already desoldered the lightning connector flex pcb.

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Remove the following chips indicated by the following silkscreen printing:

  • Q3 (chip markings: p7)
  • Q4 (chip markings: wsc7)

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

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Step 1 completed!

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Step 2

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

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Done!

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