Hello Forum!
Hai Manoj,
this is my first Post on this Forum and what better topic than this to kick off,
my Friend Manoj, if it makes you feel any better ,you are not the only one facing this Freq. problem.
i too am from India and at times the mains are at 49 and even 48.5 cycles.
Recently i have built the Digital Alarm Clock using SC8560/LM8560 and faced the same problem of Freq.
the time is slow by say 4 to 5 mins.
had to do endless Google searches for stable 50/60 HZs but in vain.
So, i decided to use simple Cmos Multivibrator CD4047 tuned at 100Hz split by 2 thru its outputs to get 50Hz.
now for the BIG question how would we be sure of the final Freq. i,e 50Hz ?
i just made a 150W inverter using a pair of Mosfets connected to the 2 Outputs of CD4047 and Connected a Black and White TV to check for the Rolling Bar on the Screen.
finally adjusted the freq. preset till i saw no rolling bar on the screen. all this trouble could be saved if one uses a Frequency Meter.
finally the fine tuned 50 Hz Square wave pulse was fed to the CLock IC, the time keeping drastically Improved when compared to Mains derived Freq.
i know this is not precise when compared to Crystal but better than our grid's mains freq.
hope my experience is of some help
arun