The Brain Machine is a simple, homemade "Sound and Light Machine
." An SLM is a device to aid meditation by synchronizing your brain activity to external stimuli...flashing lights and pulsing sounds. The synchronization occurs through a principle called "entrainment"; light and audio are pulsed at frequencies associated with different levels of brain activity and your brain "locks on to" (or "trains on") the external stimulation.
You can read about the different levels of brain activity here
on Wikipedia. When you first turn on the brain machine it generates output in the beta frequency range and works its way down to a meditative theta frequency. After keeping you there for a few minutes it speeds back up to bring you back to a wakeful state. The whole cycle takes 14 minutes and you can read more about it on the Makezine blog
. That blog post describes how to build the basic Brain Machine and is the guide I used to build mine so this instructable will focus on the changes I made to make my Brain Machine look less outrageous.
As a side note, when reading about Theremins
I heard of a phenomenon called locking that causes pendulums or electronic oscillators to lock to the same frequency when they start out running at similar enough frequencies. I don't know how related entrainment is, but it's an interesting similarity even if the principles are mostly unrelated.