hardware random noise generation

[smashedProton]

Does anyone have any experience with doing this with only jellybean parts?  It's difficult to sense thermal noise...  My thoughts are some sort of a little antenna with the gain shot way up, or to use zener noise somehow.  Please enlighten me!

[NiHaoMike]

http://dangerousprototypes.com/2012/10/22/7400-competition-entry-random-number-generator/
That's the basic idea. More realistically, you'll use opamps instead of making logic gates behave in an analog manner and a PIC instead of discrete logic. A great trick is to digitize the noise and use the last few bits. If you use a secure hash (or encryption) to whiten the noise, then take the output and XOR it with the noise before sending it back through the hash to create the next value, you can get a great deal of random numbers with relatively little input.

BTW, if you have a PC based on an Ivy Bridge CPU, then it already has a good RNG inside it. Many motherboards also have RNGs built into the chipset.
http://en.wikipedia.org/wiki/RdRand

[SeanB]

Reverse biased transistor base emitter junction, breaks down at around 7V. Feed it with 100uA and then AC couple to an opamp with a gain of 20. Use a 741 for the added noise, then use a second one to amplify 50 times. Gives a good audio range white noise.

[grenert]

What kind of frequency spectrum are you looking for?  For audio, there are a lot of circuits online with reverse biased zener diode amplified by transistors or LM386.

[asbokid]

http://www.ciphersbyritter.com/RES/NOISE.HTM
http://www.jtxp.org/tech/xr232web.htm
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.46.5555&rep=rep1&type=pdf