Electronics search engine SupplyFrame has raised $1.5 million of a $4 million third round, according to an SEC filing . Four investors have participated in the offering thus far, though specifics were not disclosed. Current investors include U.S. Venture Partners, Clearstone Venture Partners and Arcturus Capital. The $1.5 million brings total funds raised to date to $13.5 million. The Pasadena, Calif-based SupplyFrame’s search engine is free and is mostly used by professionals looking for information on certain manufacturers. It makes most of its money through advertising.