Spec Sheet Preview: The Alpha Communications® / S.T.R.™ SNT333S Switching Power Supply is used only with the 2-wire QwikBUS™ series intercom and/or video-intercom systems. The SNT333S provides the regulated 24VDC power needed to control the SP333 QwikBUS™ intelligent controller. Each SNT333S gets its power from a customer supplied power cord, and will operate on an input of 100 to 240VAC. Each 2-wire QwikBUS™ system requires a minimum of one SNT333S Switching Power Supply.