The DDA requires an audible warning from a fire alarm system to be reinforced by a visual alert in many installations such as nursing homes, hotels and offices. The unit fits Sensor Series 200 addressable dunder any standard System etector and twist fit into a standard surface or flush mounting base, enabling sounder-only units to be easily upgraded without tools. To improve the installation process, the common base is fitted with a shorting spring so that the loop wiring can be tested without either the sounder-strobe or a detector having to be installed.

The devices generate 32 different audible tones and are available with red or amber lenses. They integrate a high efficiency piezo-electric transducer with a high output LED array to give a unit that simultaneously generates a 98dB @ 1m audible signal and a 1Hz flash with a combined current draw of less than 8.7mA at 24VDC. The low current draw per unit ensures that if the maximum number of devices supported by the communications protocol are fitted to the loop, the total loop current requirement does not exceed the normal rating for the wiring and battery back-up capacity.

The design enables all popular protocols to be ported to the units via a plug-in interface module; they are optionally available with built-in isolation. The operating voltage is 15 - 32VDC and an anti-tamper feature prevents removal from the base without the use of a tool. The units are third party approved to EN54-3 and the Construction Product Directive (CPD).