When the reset button presses the capacitor charges fully. Then the positive charge comes to the base of T, through VR ad T1 turns off. This state sustain till the capacitor discharges. This interval is controlled by VR. using this we set the time. To stop the reminder we discharge the capacitor totally. When the capacitor discharge, T turn on and led glows.
Reminder
When the reset button presses the capacitor charges fully. Then the positive charge comes to the base of T, through VR ad T1 turns off. This state sustain till the capacitor discharges. This interval is controlled by VR. using this we set the time. To stop the reminder we discharge the capacitor totally. When the capacitor discharge, T turn on and led glows.