PURPOSE: To simplify constitution of conductive parts by forming the plural conductive parts to the triple concentrical circles of 24-hour wheel, providing contact pieces which contact with each other at two symmetrical points thereof and emitting successively different signals according to the rotation of the 24- hour wheel.

CONSTITUTION: The conductive parts 3W9 are provided to the double concentrical circles (a), (b) on the outside among the triple concentrical circles of the 24-hour wheel and the conductive part 10 for AM and PM is provided to the inside concentrical circle (c). These parts are respectively conducted to the common conductive part 2. On the other hand, contact pieces P1WP4 and contact pieces P5 for AM and PM are provided in the symmetrical positions thereof and are so constituted that 12 kinds of the different signals are successively emitted according to 180° rotation of the 24-hour wheel and that 12 kinds of the reverse signals are emitted according to additional 180° rotation and further that the signals identifying AM and PM are emitted. The constitution of the parts 3W9 and 10 is thus made simpler and the possibility for erroneous contact is eliminated, by which the exact detection of time is made possible and the identification of AM and PM is made possible as well.