> i don't think using the mains for refrence frequency will give >you a stable clock. Vishram, maybe not in India but here in the USA the mains are a very reliable source, accurate to within seconds per month. It varies in reliability greatly from country to country. For a thing we did for Taiwan, we were pretty certain there wouldn't be ANY power for extended periods of time. "It all depends..." Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================