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MB3 184b: Music in Shul In General and Watches and Alarm Clocks on Shabbos (338:2-3)
Having musical instruments played in Shul (in general and on Shabbos) is prohibited today.
Setting an alarm clock before Shabbos (Rav Moshe & Rav Shlomo Zalman). Setting a mechanical alarm clock.
Using an alarm clock on a mobile phone
Winding a watch or setting the correct time on Shabbos. Wearing a kinetic watch on Shabbos.