Hi erics1,

The 2.2k ohm resistors are intentional. The original firmware (from the above link) uses 400Hz for the audio. Since that was a bit too much like buzzing mosquitos, I changed it to 200Hz, and 2.2k ohm resistors work better with this lower frequency. The latest firmware is available from my website:
http://www.CornfieldElectronics.com
click on the “maker faire” button, and then click on “the latest SLM firmware”.

Modifying it to go down to to Theta, with occasional pulses of Delta would be great for helping you sleep. Putting it in a comfortable sleep mask is also a great idea. This is what I’m doing (along with using a more complex model of brain waves) in the sleep mask I’ve been working on.

Please post the results after you try things out.

Cheers,
Mitch.