"M2" Quotes from Famous Books
 ... an annunciator is one where the bell may be operated from either of two push buttons. In this case the annunciator must be constructed to give only two indications. Fig. 1 shows how the various' elements of such a circuit may be connected. B is an ordinary vibrating electric bell, M1 and M2 are the two electromagnets of the annunciator, A is a battery of several dry cells, and P1 and P2 are the push buttons from either of which the bell may ...
— The Boy Mechanic: Volume 1 - 700 Things For Boys To Do • Popular Mechanics |
