Set an interval reminder:
The interval reminder is a basic timer that will go off after the designated duration.
Our example will set a reminder to go off every 105 minutes (1 hour 45 minutes) between 7:50 AM and 10:30 PM.
From the main screen tap the clock icon located in the top right corner.
Touch the plus sign (+) in the upper right corner.
Select interval reminder.
To enable the reminder, tap the slider to show green. Designate your start time, end time, and interval.
Select a sound. Tap the back arrow in the upper left to save your choice. Then tap the back arrow a second time to save the reminder and return to the home screen.