| 摘要 |
<p>An electrical quantity sensor (1) includes, an oscillation circuit (5) for producing a clock signal of predetermined frequency, a light-emitting element (3a) which blinks at a predetermined frequency in accordance with the clock signal output from the oscillation circuit, a switching element (3b) which is optionally coupled to the light-emitting element and is brought into conduction when the light-emitting element illuminates, a transformer (4) whose primary winding (4a) is connected, by way of the switching element, to input terminals which receive a d.c. electrical signal and a synchronization detecting circuit (6) which synchronously detects an a.c. electric signal developing in a secondary winding (4b) of the transformer while the clock signal is taken as a reference, thereby producing a d.c. voltage signal corresponding to the amplitude of the d.c. electric signal.</p> |
