Below are three timer files of simple bell sounds . These are recordings that you can use to time your own practice. The 20 and 30 minute timers also include interval bells at roughly 10 minutes.
10 Minutes – this has a bell at the start and the end of a 10 minute interval, and silence in between.
20 Minutes – this has a start and end bell for 20 minutes, and also an interim bell at 10 minutes.
30 Minutes – this has the start bell and an end bell at 30 minutes, with interim bells at 10 and 20 minutes.