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.


Low current, 24 VDC electronic horn provides:

• Harmonically rich sound output suitable for either steady or pulsed operation

• Diode polarized input for connection to reverse polarity, supervised NACs

• Rugged, high impact, flame retardant red thermoplastic housing with white "FIRE" lettering (white cover is available separately)

Switch selectable horn operation modes:

• Free-Run mode tracks the output of a conventional fire alarm control panel notification appliance circuit (NAC)

• SmartSync two-wire control mode accepts horn control commands from compatible control panels (see list on page 2)

Free-Run Mode operation provides:

• Horn activated when NAC is in alarm; suitable for Temporal pattern, March Time patterns, or Coded patterns as determined by control panel operation