We will consider random Schrödinger operators in 1d, both in the discrete and the continuum setting. It is known that for a large class of potentials, Anderson localisation holds: the spectrum is pure point and the eigenfunctions are exponentially localized. In the weak disorder limit, we will show that a random Dirac operator arises « generically ». This operator displays very nice properties. Joint work with Laure Dumaz (ENS).