Vigortronix 230v toroidal transformers single primary dual secondary vigortronix vtx 146 050 109 toroidal transformer open style 50va 230v ac primary winding 2x 0 9v ac secondary windings 150mm lead length ul csa tuv en60950en60065 compliant vigortronix vtx 146 050 109 toroidal transformer 230v single primary 50va 0 9v