The Alpha Communications® AC219 annunciator control unit is used only with the AlphaEcall™, CM800, DS100 and SF202B series emergency-call and intruder alarm systems and annunciators. The AC219 is used to provide tone signal, tone silencing, tone-silenced visual indication, auxiliary (form 'C') signal relay, and 24VDC for accessory device operation. The AC219 operates on 16VAC (30VA) low-voltage Class II wiring, using our model SS106 or SS146 transformer. All AC219 connections are positive screw terminal type.