SAKURA AQS401 NFC Start-Up Modification

Adding NFC start-up to my SAKURA AQS401

The inner diameter of the decorative cover is 108.3mm, and the height is 18.5mm

NFC coil inner diameter 90mm, outer diameter 100mm

1. You need to purchase a motorcycle NFC sensor

2. Based on the official circuit diagram and the module's circuit diagram. Just connect the red wire and a set of relay's yellow or white wire (yellow recommended) together, insert it before and after the 25A fuse of the battery to get power, connect the black wire to the negative pole of the battery, and connect the remaining relay wire. Direct wiring will loosen, use a 9P plug

3. The coil of the motorcycle NFC starter is not very aesthetically pleasing, and the wire is not long enough, it can only be attached to the inside near the seat

The most troublesome part of this scheme is that, due to the change in the shape of the induction coil, (the coil engineering file is in the compressed package)

And the wiring from under the seat is about 1.3 meters long. The inductance value of the extended and modified parts does not match the capacitance of the module itself, and needs to be paralleled with a capacitor for adjustment. The size of the capacitor to be paralleled is affected by the length and diameter of the extension wire. The capacitor size suitable for me may not be suitable for you, some references are given below.

Using DuPont wire with 0.08 square mm, about 1.5 meters, parallel with a 220pF capacitor, using 0.5 square mm copper core wire, about 1.3 meters, parallel with a 470pF capacitor.
You need to test yourself to determine the capacitor size needed for your motorcycle.

You need to purchase 2P vertical surface mount components to solder on the coil, solder the capacitor between the two pins of the 2P vertical surface mount components, and use 2P male and female housings to make extension wires

(For the coil part, use JLCPCB to get 5 pieces for free, the engineering and order files are in the compressed package, pay attention to the thickness of the board material when ordering, which is 0.8mm)

The installation principle for other motorcycle models is similar, you need to check the circuit diagram in your motorcycle manual