The Boy Electrician; Practical Plans for Electrical Apparatus for Work and Play, with an Explanation of the Principles of Every-Day Electricity

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 edition. Excerpt: ...binding-posts, A and B, mounted on the end of the receiver. A hook is also provided so that the receiver may be hung up. The diaphragm is a circular piece of thin sheet-iron, two and one-half inches in diameter. It is placed over the shell, and the bar magnet adjusted until the end almost touches the diaphragm. The magnet should fit into the hole very tightly, so that it will have to be driven in order to be moved back and forth. The diaphragm is held in place by a hard-wood cap, two and three-quarter inches in diameter and having a hole three-quarters of an inch in diameter in the center. The cap is held to the shell by means of four small brass screws. The receiver is now completed and should give a loud click each time that a battery is connected or disconnected from the two posts, A and B. The original Bell telephone apparatus was made up simply of two receivers without any battery or transmitter. In such a case the current is generated by "induction." The receiver is used to speak through as well as to hear through. This method of telephoning is unsatisfactory over any appreciable distances. The time utilized in making a transmitter will be well spent.. A simple form of transmitter is shown in Figure 148. The wooden back, B, is three and one-half inches square and three-quarters of an inch thick. The front face of the block is hollowed out in the center as shown in the crosssection view. The face-plate, A, is two and one-half inches square and one-half an inch thick. A hole, seven-eighths of an inch in diameter, is bored through the center. One side is then hollowed out to a diameter of one and three-quarter inches, so as to give space for the diaphragm to vibrate as shown in the cross-sectional drawing._. The carbon...