Vigortronix 230v toroidal transformers single primary dual secondary vigortronix vtx 146 500 140 toroidal transformer open style 500va 230v ac primary winding 2x 0 40v ac secondary windings 150mm lead length ul csa tuv en60950en60065 compliant vigortronix vtx 146 500 140 500va toroidal transformer 230v primary 2 x 40v