BCI part 3 – The basic Headset simple modification

Sep 9, 2014 | | Say something

In the preceding post I described in detail the inside electronics of the Mindflex headset, especially the connections to the NeuroSky TGAM1 module. Here I describe the basic modification of the headset as covered elsewhere on the Internet and then explain some of the safety issues of wired connections to an Arduino and beyond. At a later date in another post I will describe how to minimise electrical safety by means of low powered radio modules. This simple step here I used as a proving ground to get the device working on the Arduino and the visualisation software.

Several sources on the Internet claim it is easy to hack, only two wires need to be soldered on to the output of the NeuroSky Chip/module and this will provide a continuous stream of eeg data that can be connected to an Arduino, leaving the game intact should anyone also want to play it.

There are concerns that with the electrodes making contact with the human body, especially on the head, in the brain region over safety with other electrical connections – Arduino and laptop/computer being the ultimate destination for the data.

There would appear to be a number of ways to improve on the safety aspect by providing isolation in the way of either an optical or radio link at some stage on the headset, of course retaining original battery power. Anyone wanting to provide optical isolation, look at 6N138 or 6N137, check speed. 470 resistor in series with T to cathode, anode to V. on other side vcc to pin 8, 1k pin 7 and 5, gnd to pin 5 out pin 6.Make sure to keep supply and ground rails separate to maintain isolation.

Looking at things in a block form then one easy way could be to use the wireless apparatus within the headset, picking up the output, the other side of the radio link within the console. This could mean a larger modification. It does not seem possible to use the in-built wireless module as the microprocessor within the headset does some unknown things with the data from the TGAM1 module.

There is also power consumption, if the standard modification is followed, then there is a lot of unused electronics that is still being powered. It seems all that needs powering is the NeuroSky chip.

It should be possible to de-solder the 9 pins and remove the Neurosky module and use it elsewhere providing it with a 3.3V supply. Alternately these pins could be de-soldered and the main PCB removed and discarded leaving the housing available to accommodate other electronics along with the module. I might explore more on this at a later date.

For initial modification, I soldered on a blue wire to T pin and pink wire to ground pin on the TGAM1 module and brought these wires out through the existing portal where the ear-clip cable exits. There is no need to drill a hole in the case of the headset as suggested by some Internet sources.

In the next part I will describe connecting up to the Arduino, the Arduino and visualiser software to get the system running as a first step in my experiments.


Posted in: Brain Control Interface

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