The ornamental design for a voltagedetector, as shown and described.
FIG. 1 is a perspective view of a voltage detector;
FIG. 2 is a front view of the voltage detector shown in FIG. 1;
FIG. 3 is a rear view of the voltage detector device shown in FIG. 1;
FIG. 4 is a top view of the voltage detector shown in FIG. 1;
FIG. 5 is a side view of the voltage detector shown in FIG. 1; and,
FIG. 6 is a bottom view of the voltage detector shown in FIG. 1.
The broken line showing of structural features is included for the purpose of illustrating non-claimed subject matter and forms no part of the claimed design.