Circuit shows that music reminder to make the refrigerator to be closed . The circuit consists of the rectifier circuit from the buck regulator circuit, delay circuit , music IC CIC2851E, speakers and other components. One buck regulator circuit for the entire circuit rectification provides the DC voltage of about 3V . When you open the refrigerator door, AN switch connected to charge capacitor C3 through R3 as the charge for , BG1 the base potential increases approximately 20 minutes delay , C3 on the voltage to BG1 turn , BG2 closed. The corresponding triggers to CIC2851E work , the output of the music signal to drive speakers amplified by BG3 Y gives a ” jingle sound … … ” the music , to remind the owner of the fridge to close the fridge quickly. Fridge door does not pass, the music more than sound . The length of delay time can be selected to take food , generally between 5 to 15 seconds . This circuit take 20 seconds. DW at both ends of the circuit required voltage is about 3V, if too high, easy to damage the IC . Resistor R6 to adjust the speed of musical rhythm , which range from 20kO = R6 = 120kO.