Enter the follwing time value properly and set the Timer by clicking Start button, to reset the timer click on Reset button.
Countdown timer requires start time in HH, MM & SS, based on values of hours, minutes & seconds, it will start the countdown timer, once it reaches to 00:00:00, it will start the counterdown timer alarm beeps, you can click on Restart button, if you want to run the same countdown timer again or click on Reset to stop the alarm beep & reset the countdown timer values to default.