A smoke alarm device comprises an optical smoke sensor including a light emitting diode (IRED) and a photo-detector (PD) mounted in a chamber, and a circuit with a processor (U1), a user interface, and a sound emitter (HORN). The processor is adapted to cause the light emitter (IRED) to be pulsed by a drive circuit. The processor (U1) enters a de-sensitized mode for at least a first and a second period upon receipt of user commands. It automatically performs dust compensation re-calibration in the second or a subsequent de-sensitized period. The re-calibration is implemented in a duration of less than twenty minutes. Also, the processor directs emission of an indicator that the device is de-sensitized while it is in the de-sensitized mode. The processor ceases alarming for a period in excess of 4 hours if it performs dust compensation and also receives a hush instruction from a user. The circuit includes a current source for the light emitter to maintain a uniform current through said emitter. The current source comprises a light emitter control switch transistor (Q3) in series with the light emitter, a resistor (R25) connected between the light emitter switch (Q3) and ground, a diode (U3) providing a voltage reference for a base of a light emitter switch (Q3), and a control switch (QP2) linked with the base of the light emitter switch (Q3), and means in the processor (U1) for activating the control switch (QP2).