SIMPLEX 566-520A Amplifier Circuit Board NAC

SIMPLEX 566-520A Amplifier Circuit Board NAC is a 100-watt analog NAC amplifier module used inside Simplex 4100-series fire alarm panels to drive notification appliance circuits. Sold as an Amp PC Board Only, it is part of the family that includes 566-521A and is designed to provide multiple Class B NAC outputs with constant supervision. In official Simplex service literature, the related 566-521 variant is described as an Analog 100-Watt Amplifier with six Class B NACs and constant supervision, indicating the 566 family supports multi-NAC configurations. Catalog entries show power configurations such as 120 VAC input with 25 V RMS NAC outputs, as well as variants for 70 V RMS and Canada-specific 25 V RMS setups, all intended to integrate with Simplex power supplies and NAC wiring.