An electronic circuit comprising an input powered part and a supply powered part, wherein the input powered is arranged to receive one or more inputs and generate one or more outputs as a function of the or each input, the/or each output controlling the supply powered part of the circuit. The input powered part may be powered substantially or exclusively by its input(s). The input powered may be capable of operating when drawing power of less than 10 nW of power. The input powered part may be capable of operating from an input which rises with no minimum gradient, preferably from 0V. One or more inputs to the input powered part may be connected to a respective sensor, preferably a voltage generating sensor such that the input powered part of the circuit is at least substantially, and preferably exclusively, powered by the/or each sensor.