An ice detector circuit for sensing an ice deposition on a sensing surface of an ice detector probe from an air mass flowing relative to the probe. The probe includes a heater to heat the sensing surface and a temperature sensor for sensing the sensing surface temperature during heating. The temperature sensor provides the circuit with an output having a level varying as a function of the sensing surface temperature. The circuit includes a controller which selectively energizes the heater, a timer which provides a timing output representative of a time interval elapsed between selected temperature sensor output levels, and computing means, such as a microprocessor, which computes an output representative of ice deposition as a function of a predetermined relationship between ice deposition and the timing output.
