Diameter: 16 inches (at wall) Depth: 4 inches

So-called slave or secondary dial clocks depend on a master clock to provide brief timed electrical impulses, generally once a minute, to advance the hands in synchronism with the master clock. They are connected by low voltage wiring often along with bell circuits.

Height: 15.75 inches Width: 15.75 inches Depth: 3.75 inches

The mechanisms are usually simple ratchet wheel gear train mechanisms with an electromagnet linked to the ratchet pawl. Electrically, they operate on different voltages depending on series or parallel connection choice; from three to forty-eight volts. Some later models however, use a carrier signal imposed on 120 volt utility power circuits.