'Controlling' random variables

I'm working with a friend on developing a USB stick with a reverse-bias transistor to create random bits. We have a working prototype, but I'm worried about how to 'correct' the samples.

This design has a sort of 'floating ground' on the signal being sampled, and we can move it's center up or down to affect how many ones vs zeroes there are. We can tune it to be exactly 50%, but I'm wondering how much fiddling we can do and still call it 'random'.

Is sampling 1000 bits, checking if they're 50/50 ones and zeroes, and then adjusting up or down the way to do this? Should there be a bigger window, smaller window, random window, or is there something more sophisticated we can do?

Who would be knowledgeable on this entropy/random stuff besides the crypto community?

Thanks for reading