Dual Adjustable with Power Transformer The CBC-550 is a dual channel adjustable voltage control with optically coupled switching for 24 and 90 volt electric clutches and brakes. These controls can be set up to energize the two outputs alternately (single) or simultaneously (dual). The CBC-550 has a power transformer which will operate with a 120, 220, 240, 380, or 480 VAC input.