Part 6 (2/2)
CHARGING THE CELLS--The charge of the current must never be less than 25 volts Each cell has an output, in voltage, of about 2 volts, hence if we have, say, 10 cells, we e these in one line, or in series, as it is called, so far as the connections are concerned, and charge them with a dynamo, or other electrical source, which shows a pressure of 25 volts, as illustrated in Fig 64, or, instead of this, we may put the 65, and use 125 volts to charge with In this case it will take double the tie used in the first case
The positive pole of the dynamo should be connected with the positive pole of the accuative When this has been done run up the e of the cells Thus, if we have 50 cells in parallel, like in Fig 64, at least 125 volts will be required, and the excess necessary should bring up the voltage in the dyna 65_ PARALLEL SERIES]
[Illustration: _Fig 66_ CHARGING CIRCUIT]
THE INITIAL CHARGE--It is usual initially to charge the battery fro from 36 to 40 hours, and to let it stand for 12 or 15 hours, after which to re-charge, until the positive plates have turned to a chocolate color, and the negative plates to a slate or gray color, and both plates give off large bubbles of gas
In charging, the temperature of the electrolyte should not exceed 100 Fahrenheit
When using the accued
THE CHARGING CIRCUIT--The diagra circuit is formed The lamps are connected up in parallel, as illustrated Each 16-candle-power 105-volt la we have a dynae a 4-volt accuo to the accue of 2 amperes, four of these lamps should be connected up in parallel If 3 amperes are required, use 6 lamps, and so on
CHAPTER IX
THE TELEGRAPH
The telegraph is a very si more or less than a switch which turns the current on and off alternately
The signals sent over the wires are simply the audible sounds nets
MECHANISM IN TELEGRAPH CIRCUITS--A telegraph circuit requires three pieces of mechanism at each station, namely, a key used by the sender, a sounder for the receiver, and a battery
THE SENDING KEY--The base of the sending instru, four inches wide, and three-quarters of an inch thick,hths by one-half inch in thickness and six inches long Midway between its ends is a cross hole, to receive the pivot pin (B), which also passes through a pair ofa screw to hold one of the line wires, and the other bracket having a ed thereto This switch bar, like the brackets, is made of brass, one-half inch wide by one-sixteenth of an inch thick
Below the forward end of the key (A) is a cross bar of brass (F), screwed to the base by a screw at one end, to receive the other line wire Directly below the key (A) is a screw (G), so that the key will strike it when moved doardly The other end of the bar (F) contacts with the forward end of the switch bar (E) when the latter is67_ TELEGRAPH SENDING KEY]
The forward end of the key (A) has a knob (H) for the fingers, and the rear end has an elastic (I) attached thereto which is secured to the end of the base, so that, norainst the base and away from the screw head (G) The head (J) of a screw projects from the base at its rear end Key A contacts with it
When the key A contacts with the screw heads G, J, a click is produced, one when the key is pressed down and the other when the key is released
You will notice that the two plates C, F are connected up in circuit with the battery, so that, as the switch E is thrown, so as to be out of contact, the circuit is open, and may be closed either by the key A or the switch E The use of the switch will be illustrated in connection with the sounder
[Illustration: _Fig 68_ TELEGRAPH SOUNDER]
When the key A is depressed, the circuit of course goes through plate C, key A and plate F to the station signalled
THE SOUNDER--The sounder is the instru 68 this is shown in perspective The base is six inches long and four inches wide, being made, preferably, of wood Near the forward end is nets (A, A), with their terminal wires connected up with plates B, B', to which the line wires are attached