AC POWER SOURCE TIMER PROTECTED FROM POWER FAILURE

摘要

PURPOSE:To obtain an ac timer protected from electric power failure keeping the equal precision to that of an ac power source synchronized timer. CONSTITUTION:The first clock signal generator 4 generates the clock signal (a) based on the ac frequency of an AC power source 6. The second clock signal generator 5 generates the clock signal (b) equal to the clock signal (a) based on the signal supplied from a quarty oscillation element. An electric failure discriminator 1 discriminates the electric power failure of the AC power source 6, and generates an electric failure signal (d). A clock signal selector 2 is switched so that the clock signal (a) is selected in normal electric power supply and the clock signal (b) is selected in electric power failure based on the electric failure signal (d) supplied from the electric power failure discriminator 1, and the clock signal is transmitted to the body 3.