| 摘要 |
An electrical test device for use by an electrician in testing circuits. The device includes a voltage sensor, display, and steady current source. The voltage sensor monitors the type of voltage (AC or DC) between the two conductors, and provides a signal to the display which responsively displays the type of voltage and the voltage level. The power supply has a steady current source that is in series with a tactile transducer, so that the test device may measure a broad range of voltages while only a limited amount of current flows through the voltage sensor. Consequently, lower cost components may be used in the voltage sensor. In another embodiment, the tester also includes a substantially independent continuity tester. The continuity tester includes its own power supply and alarm to indicate the continuity of a conductor and, thus, may operate even if the voltage sensor and display become inoperable. Further, the device may include a phase control for monitoring any alternating voltage sensed by the testing device. The phase control provides an enable signal for only a relatively small segment of the phase of an alternating voltage signal. Thus, the phase control enables the voltage sensor to sense voltage only for a relatively short period of every cycle of the voltage applied to the tester. Accordingly, a lower cost voltage sensor may be employed within the tester.
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