I want to build some type of electrical circuit to detect alpha, beta , theta etc. waves from the brain and maybe even show the frequency in hertz . Or at first, generate a higher power wave for my scope to read. How can this be achieved? And what would I use to pickup the waves?
To get the signal use AgCl electrode, and electrolytic gel, on various points on head, you can start with three points on forehead,look of 10-20 system of EEG for the placement of electrodes.
For the circuit part, you'll need a pre-amplifier, a nice instrumentation amplifier, a notch filter, 50/60Hz depending on your location, then a 7Hz high pass filter, to filter the galvanic response from the skin and a low pass filter at 30Hz cut-off frequency. The link below gives a step by step process.