Here’s a link to the Blue and Black USB Schumann frequency generators from Hong Kong sold on eBay. So cute! I use the BLACK device which is more accurate than the BLUE. The listing is for the BLUE device. To order a BLACK unit you need to specify quantity of 2 of the BLUE units. Then you’ll get one BLACK. Yes, I know it’s a little confusing.
Note: you want to position the USB device (or any Schumann device) at height of about 5 feet so you’ll need a standard 2 amp wall wart and 6 ft long USB cable for each device.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F273903516414
Note: you want to position the USB device (or any Schumann device) at height of about 5 feet so you’ll need a standard 2 amp wall wart and 6 ft long USB cable for each device.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F273903516414