"About that time, I began to notice my mains-synched digital clocks began to not keep accurate time." But do your analog mains synched clocks keep time? We have dropped using line frequency for our tower and street clock controls as electrical noise - switching power supplies and non-zero crossing dimmers adds a good deal of noise to the power system - enough to run the counters fast - I suppose we could add a equivalent of a PLL but TXO are cheaper. Thomas D. Erb p: 508-359-4396 f: 508-359-4482 a: 97 West Street, Medfield, MA 02052 USA e: tde@electrictime.com w: www.electrictime.com Tower & Street Clocks Since 1928