https://github.com/waywardgeek/infnoise https://www.crowdsupply.com/13-37/infinite-noise-trng
Speed is limited by the speed of a gain stage and a comparator, and can run in excess of 100 Mbit/second per second with high performance components. Cheap solutions with CMOS quad op-amps can run at 8Mbit/second.
This implementation uses Keccak-1600 with cryptographically secure reseeding of more than 400 bits of entropy at a time, overcoming a trickle in/out problem present in the GNU/Linux /dev/random system. Users who need many megabytes per second of data for use in cryptography can set the outputMultiplier as high as they like, which causes Keccak to generate outputMultiplier*256 bits per reseeding by the Infinite Noise TRNG.
In your link they supply it from a battery, but if you want this as a RNG for a computer you aren't going to want a battery...
You can use a regulator to supply it but the noise from the regulator will be a critical consideration since the noise from the regulator may be predictable to an outside observer. So that deserves a careful design.
This sort of design seems simpler to get right at least electronics wise, https://github.com/waywardgeek/infnoise but OTOH the underlying noise process is a lot less clear than a zener, and I would worry that it's picking up external RF.
https://github.com/waywardgeek/infnoise
https://www.tindie.com/products/WaywardGeek/infinite-noise-t...
I remember him from the CipherShed project that was trying to reboot TrueCrypt. Discussed securing the build system & distribution. He seemed smart. I have no experience with Tindie, though, so I'd appreciate feedback from anyone that knows about them. He also includes BOM, etc on the GitHub so someone can source and build it themselves.