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Brain Wave Genereation

Theory behind BrainWave Generator
EEG and the brain's state
EEG (Electroencephalography) technology is used to measure brain's electrical vibrations from the surface of the scalp. The resulting EEG pattern will contain frequency elements mainly below 30Hz. The frequencies are categorized into four states as follows: State Frequency range Amplitude State of mind
Delta 0.5Hz - 4Hz high (up to 200uV) Deep sleep
Theta 4Hz - 8Hz low (5uV - 20uV) Drowsiness (also first stage of sleep)
Alpha 8Hz - 14Hz high (up to 200uV) Relaxed but alert
Beta 14Hz - 30Hz low (less than 10uV) Highly alert and focused
The dominant frequency in the EEG pattern determines what shall be called the current state of the brain. If the amplitude of the alpha range frequencies is highest, then the brain is said to be in the alpha stage. Note, that other frequencies still exist and it is impossible to give any "exact frequency your brain is operating on". However, later references to the brain states use the simplification of assuming that such a single frequency exists.
Entraining the brain to a desired state
If external stimulus is applied to the brain, it becomes possible to entrain the brain frequency from one stage to another. For example, if a person is in beta stage (highly alert) and a stimulus of 10Hz is applied to his/her brain for some time, the brain frequency is likely to change towards the applied stimulus. The effect will be relaxing to the person. This phenomenon is also called frequency following response.
When the brain's state is close to the applied stimulus, entrainment works more efficiently. Thus, when doing a sweep from one frequency to another, the starting frequency should be as close to your current brain state as possible. The sweep speed should be such that your brain's state changes steadily with it, so that the difference never gets very large. In practice, it is difficult to determine your brain state without extra equipment (like...