Alternative Neurosky MindWave

Dear all,

Since the Neurosky MindWave it is no longer available here, I would like to build a replica of it

Do you happen to know how the signals are acquired and processed? As far as I know, there are just 3 dry electrodes 3, one at Fp1 and the remaining two for earlobe. How is the information processed in order to get the attention/meditation signals?

Thanks,