  We investigate electron transport in two quantum circuits with mutual Coulomb
interaction. The first circuit is a double quantum dot connected to two
electron reservoirs, while the second one is a quantum point contact in the
weak tunneling limit. The coupling is such that an electron in the first
circuit enhances the barrier of the point contact and, thus, reduces its
conductivity. While such setups are frequently used as charge monitors, we
focus on two different aspects. First, we derive transport coefficients which
have recently been employed for testing generalized equilibrium conditions
known as exchange fluctuation relations. These formally exact relations allows
us to test the consistency of our master equation approach. Second, a biased
point contact entails noise on the DQD and induces non-equilibrium phenomena
such as a ratchet current.
