| 摘要 |
<p>A solid state relay provides for a discontinuous transfer contact function. The solid state relay includes a first field effect transistor (FET) in a first switch, and second and third FETs in a second switch. The first and second FETs are each connected with AC responsive bias circuits for biasing the respective FETs into a non conductive condition. A control circuit operates the first and second switches to provide a transfer contact function. In a switching transition between a supply of a talking battery via the second switch, to a telephone line, to a supply of a ringing battery line via the first switch to the telephone line, the third FET is operated to increase impedance between the talking battery supply and the second FET, to permit AC voltage from the ringing battery supply to bias the second FET OFF.</p> |
