Teng! Teng! Sound school bell rang, students began to enter their respective kekelas, That story Bel School antiquity. Of course you still remember the school bell clang sound when you re still in Elementary school (SD), junior and high school students when the clock showed 7:00 pm. Over time the school bell and the advancement of technology is now beginning to more advanced. Starting with the changes using electronic devices that use a transistor to use Integrated Circuit (IC) to replace a school bell or old iron bell.-Teng! Teng! Teng! Sound school bell rang, students began to enter their respective kekelas, That story Bel School antiquity. Of course you still remember the school bell clang sound when you re still in Elementary school (SD), junior and high school students when the clock showed 7:00 pm. Over time the school bell and the advancement of technology is now beginning to more advanced. Starting with the changes using electronic devices that use a transistor to use Integrated Circuit (IC) to replace a school bell or old iron bell.