The F1000-650 Discovery Photoelectric Smoke Detector has a moulded self-extinguishing white polycarbonate case with wind resistant smoke inlets. It uses the same outer case as the F1000-550 Addressable Ionization Smoke Monitor and is distinguished by the indicator LED which is clear in standby and red in alarm. Within the case is a printed circuit board which on one side has the light proof labyrinth chamber with integral gauze surrounding the optical measuring system and on the other the address capture, signal processing, and communication electronics. An infra-red (IR) light emitting diode (LED) within its collimator is arranged at an obtuse angle to the photo-diode. The photo-diode has an integral daylight filter.