A system includes a two-conductor loop in which the loop current or current signal is controlled by a loop current controller to be proportional to a signal output from a sensor. The system further includes energy harvesting circuity in electrical connection with the two-conductor loop which includes a second current controller in parallel electrical connection with the loop current controller and a power converter in electrical connection with the second current controller. The second current controls a portion of current drawn from the two-conductor loop and delivered to the power converter from an output port thereof. The portion of the current drawn from the two-conductor loop is returned to the loop current controller from the energy harvesting circuit. Noise in the portion of the current drawn from the two-conductor loop by the second current controller is controlled by the second current controller to be below a predetermined threshold.