White noise generator transistor voltage question
This circuit amplifies the noise caused by the transistor Emitter-Base junction avalanching. The reverse breakdown voltage is usually 6-7V so it definitely won't work at 5V. 

If you want something to work from a 5V supply you can step up the 5V to ~9V, using something like an ICL7660 (charge pump) or a boost regulator, or you could use a totally different principle and build a PRNG (pseudo-random number generator) using a microcontroller.