The working of the clock is dependent upon the power grid, that is, the electrical supply. The pages are held back by a usually sliver colored metal tab, which gradually releases each number as the motor turns the wheels. In this case, the book is held vertically with half of the number on each page. There is one wheel for the hours and one for the minutes. The "pages" or tiles containing the numbers are attached to what could be called a wheel (sort of like a ferris wheel) and appear like an open book. The clocks use what's known as a split flap mechanism. Following this will be a movie of the examination of a flip clock mechanism.
This article will discuss the basic workings of the fip clock. Today, flip clocks bring back memories of the "space age" for those who lived it, and today are sought out for those interested in retro home decor. The mechanical design won awards back in the day (late 60s to 70s) and the minute by minute flipping of numbers was found to be mesmerizing by many. One of the things that makes flip clocks so interesting, is the fact that while they are digital clocks, and were considered quite "modern" in their day, they are purely mechanical, or more precisely, electromechanical.