TrueAlert non-addressable horn model 4901-9820 is an audible notification appliance with a loud and penetrating, harmonically rich sound that can be controlled either directly from a standard NAC (freerun operation mode) or by the SmartSync two-wire operation mode. Standard (free-run) operation mode. In the free-run mode, a positive voltage from the controlling NAC will activate the horn according to the desired output of continuous or coded output per the controlling NAC’s capabilities.

SmartSync mode. When selected for SmartSync mode and used with compatible Simplex control (refer to list on page 2), this horn can be wired onto the same two-wire NAC circuit as visible appliances but with separately controlled operation. Typical applications are audible notification activated as “onuntil-silenced” and visible notification appliances activated “on-untilreset.” In addition, visible appliances (strobes) on the same circuit are activated with synchronized flashes. SmartSync control two-wire advantage. Allowing these separate controls to be carried on the same two-wire NAC circuit can significantly reduce installation time and expense for both retrofit and new construction. Flexible mounting. This horn can be semi-flush or surface mounted on a standard single gang, double gang, or 4″ square (102 mm) electrical box. Optional accessories are available to increase mounting and application flexibility.