Bell Timer
Count down to the end of a lesson period, at a clock time or after a fixed length.
What is Bell Timer?
A period has an end time, not a length: lessons finish at 09:30, whatever the timetable did to the start. A bell timer therefore works from a wall-clock target, showing how long is left before you need to stop and pack away — and it should still work if you set it up in the middle of a lesson when the target time has already passed today.
How it works
The countdown is armed against the next occurrence of the clock time you enter, so a 09:30 bell set at lunchtime counts to tomorrow rather than firing immediately or refusing the value. The remaining time is recomputed from that deadline rather than decremented, so the bell is punctual even if the tab was throttled. A fixed-period mode is there for activities that are not tied to the timetable, and the chime is generated locally.
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Examples
Realistic sample
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Common mistakes
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