It may mean that the ratio of the output voltage of an electric circuit to the input voltage should be doubled.
ɪt mˈeɪ mˈiːn ðætðə ɹˈeɪʃɪˌoʊ ʌvðɪ ˈaʊtpʊt vˈoʊltɪdʒ əvən ᵻlˈɛktɹɪk sˈɜːkɪt tə ðɪ ˈɪnpʊt vˈoʊltɪdʒ ʃˌʊd biː dˈʌbəld.