PLUME – The transmitting coil + Serial Over USB


After an intense weekend, here is a summary of chat I did.

On my lab work , I advanced on the use of serial over USB. After some unfruitful hours, to try to understand how ChibiOS works, I managed to activate the serial communication over USB. So my card is finally recognized as an USB device. It now remains to me to implement a shell via the advanced functions of ChibiOS, to communicate and control my card easily.

About the Plume project, whereas I was following the work of MarcO and Olivier on the receiving coils , I worked on the transmitting coil. Indeed , we must find a way to power it efficiently and with enough intensity to generate a strong magnetic field. Thus, my present solution is to use an H-bridge for generating a slot signal for energizing the coil. I am trying to think to add a capacitor in series to create a resonant LC system with a high Q. I now need to choose the capacitor.

It also remains to check that this arrangement is viable by testing. After quick tries, we are able to transmit and receive a usable signal on 1m. This is for the weak point, but we think we can improve this value.

So I ‘m planning to re-analyse the razer hydra to understand how the signal is generated. Unfortunately, their PCB is unclear and I can not find documentation about some components.

On the other hand , I began to think about the choice of the components that we will use (alim, charge controller , … )

Finally, with the help of Benjamin , I have started to play with the BLE card and LEDs. 🙂

Good evening .


Guénolé Lallement


2 comments to PLUME – The transmitting coil + Serial Over USB

  • alexandre

    For a H bridge driver, you may need to put the capacitor in parallel rather than in series.
    It mostly depends if you have a high impedance, high voltage power source or a high current, low impedance one. Spice simulations of the sysyem, including the power source impedance and the coil impedance may be needed. For maximal power, additional inductors or transformers may be needed

  • Usual setup in resonant energy transfer is series LC in the emitting coil (to maximize coil current) and parallel LC in the receiver (to maximize voltage).