Electric School Bells
What a great invention by Joseph Henry (the father of inductance), they are so good and simple plus use very little power. There was an electric bell at Oxford University that rang for over 150 years. This would suggest electric bells are very reliable. Electric Bells for schools come in various sizes and voltages AC and DC. If you are looking for an Electric Bell make sure you get a Bell rated for outdoors (i.e. being waterproof). When electric bells are used in schools it is very easy to press the button and all the bells ring at once. Then came the smart bell, i.e the no hands model.