A lot of people think only old style clocks with synchronous motors are affected by the mains frequency. This is not the case, and it is surprising how many new electronic clocks, including alarm clocks, use a calculation based on the mains frequency rather than a highly accurate chrystal oscillator. I guess this is because the calculation results in a cheaper clock for the achieved accuracy.
A lot of people think only old style clocks with synchronous motors are affected by the mains frequency. This is not the case, and it is surprising how many new electronic clocks, including alarm clocks, use a calculation based on the mains frequency rather than a highly accurate chrystal oscillator. I guess this is because the calculation results in a cheaper clock for the achieved accuracy.