APOLLO Discovery Ionisation Smoke Detector Part No. 58000-500 Specifications are typical at 24V, 23°C and 50% relative humidity unless otherwise stated. Detection principle: Ionisation chamber Chamber configuration: Twin compensating chambers using one single sided ionising radiation source Radioactive isotope: Americium 241 Activity: 33.3 kBq, 0.9μCi Supply wiring: Two-wire supply, polarity insensitive Terminal functions: L1 & amp; L2 supply in and out connections +R remote indicator positive connection (internal 2.2kΩ resistance to positive) –R remote indicator negative connection (internal 2.2kΩ resistance to negative) Operating voltage: 17–28V DC Communication protocol: Discovery, XP95 & amp; CoreProtocol compatible 5-9V peak to peak Quiescent current: 380μA