[Unit]
Description=Fires chime.service every 15 minutes, making a chime sound

[Install]
WantedBy=multi-user.target

[Timer]
# > Values may be suffixed with "/" and a repetition value, which indicates that the value itself and the value plus all multiples of the repetition value are matched.
# - SYSTEMD.TIME(7)
OnCalendar=*:00/15