Norman H. Schneider

“ The Samson cell has a large zinc plate bent in the form of a cylinder, the carbon-manganese combination standing in the centre of it.
The dry cell also has a large zinc, the internal resistance being thus much lowered, the current output is increased. This is by reason of Ohm’s law, which teaches that to increase the current flow, either the voltage of the battery must be increased, or the resistance decreased.
But increased current means lessened life; there is only just so much energy in a cell mainly dependent on the quantity of chemicals. ”

“ Sparking at the breaking contacts of an electric bell is detrimental to the platinum points, and many remedies have been devised to overcome it.
Sparking is due to the self-induction of one turn of the wire coil acting on its neighbor, and this property is utilized in the gas engine, or gas-lighting spark coil, where a fat spark is needed to ignite gas. ”

“ Among all the applications of electricity to domestic or commercial uses, few are as widespread as the electric bell. Practically every building used for a dwelling, storage or manufacture requires an electric bell, annunciator or alarm system. ”

“ It is often better to go entirely around a room than to cross below a door.
If a door must be crossed the wire may either run up one side of the frame and down the other or laid beneath the carpet on the sill. The former is preferable, but takes more wire.
In many houses the bell wire as well as the battery wire may be run across the cellar beams (Fig. 25) , in which case bore a second hole for it near the push; do not draw it through the same hole as the push to battery wire. And, of course, here work upwards with the spool in the cellar. ”

“ A thermostat much used in fire alarm work has a thin metal chamber which is air tight. An increase of temperature causes the air to expand, which swells out the walls of the chamber and closes an electric circuit.
Fig. 40
The mercurial thermostat shown in Fig. 39 has a glass tube T and bulb containing mercury. Into each end is sealed a platinum wire P P. Upon the temperature rising to a predetermined degree, the expanded mercury completes the circuit between P P and the battery C and bell B are put in operation. ”

“ This continual making and breaking of the circuit keeps up as long as the push is pressed, a ball mounted on A by means of a rod strikes against the gong G causing a continuous ringing of the bell. The wires leading between the bell, battery cell and push must all be insulated, that is, covered with cotton, rubber, etc., which prevents the leakage of current should two wires cross each other. Copper wire is mostly used for circuits indoors, the details of the kind and size of wire will be given later on. ”

“ As the short, or shunt, circuit is very much lower in resistance than the wire on the magnet coils, the main current flows around the latter and they do not become energized. The sparking at the shunting contact screw is much less than it would be at the ordinary breaking contact screw, and the platinum points last longer. ”

“ Thermostats may be operated on open or closed circuits, that is, they may give the alarm by closing a circuit and ringing a bell, or by opening one and releasing a contact spring as in the burglar alarm system to be described later. ”

“ The form of combination floor and table push in Fig. 20 is the most solidly constructed device of its kind. The lower part is set in a hole bored in the flooring, the metal flange keeping it in place and preventing its slipping through.
21 The floor push attachment works as follows: The central metal rod is divided into two parts B D, by an insulating piece of hard rubber. When depressed against the action of the spiral spring by the foot, the upper part B connects together the contact springs A C, closing the circuit of bell and battery. ”

“ It is often desired to have the hammer give only one stroke for each pressure of the push, as in signaling with a code of taps; in this case a single-stroke bell is used. The circuit from the binding posts is then directly through the magnet coils without any break at the contact screw, as in Fig. 6.
Fig. 5 Fig. 6 Fig. 7
In adjusting such a bell to give a clear sound, press the armature up against the iron magnet cores and then bend back the hammer until it just clears the gong. The spring of the hammer wire will carry the hammer sufficiently forward to hit the gong. ”

“ Fig. 60
66 In general the wires leading from the push buttons on the different floors to the bell or annunciator in the elevator, are flexible and made up into a cable. One end of this cable is attached to the underside of the elevator car, the other end being fixed usually to the elevator wall, at a point midway between the top and bottom of the shaft.
In Fig. 61 is shown a diagram of the general circuit used, details of course differing in each installation.
One point to be taken care of in elevator work is the attachment of the cables. ”

“ Cells may be grouped in a battery to get increased voltage, or increased amperage. When connected for the former, they are in series, the carbon of one is connected to the zinc of the next, and so on.
If all the carbons are connected together and all the zincs, they are in multiple, and will give the8 same voltage as of one cell but the combined amperage of all.
In ordinary bell work the series is the general connection, the higher the resistance of the circuit, or the longer the wires, the more voltage is required. ”

“ Take the case of an ordinary door bell with the push at the front door, the bell in the kitchen and the battery in the cellar. If possible get the wire on two spools; it will simplify matters if both wires are of different colors. Starting at the push, have a foot of each wire for connection and slack, and fasten each wire lightly to the woodwork with27 staples, or double-pointed tacks, never putting two wires under one staple nor driving in a staple so it cuts the insulation. Some cases will require a staple about every foot, on straight runs sometimes every three feet. ”

“ Wiring up an Annunciator.
A diagram of the connections for an annunciator with a separate bell is given in Fig. 57. Where the bell is contained in the case a terminal will be generally found for connection.
Fig. 57
The figure shows a wire running from the battery to one side of each push button. This is the common return, or battery wire, and saves installing two wires from each push. It should be larger, however, than the rest of the wires, generally about No. 16 B. & S.
All the wires for an annunciator should be run before connecting up. ”

“ M M are coils of insulated wire wound on soft iron cores. A is a soft iron armature mounted on a flat spring so that it is normally kept a slight distance away from the soft iron cores. S is a brass screw with a platinum tip touching a platinum disc on a spring attached to the armature.
When the push button P is pressed down, its two brass springs touch each other, the current from the battery cell B then flows through the wire W, through the push P, through the coils M M, along A to the platinum disc, out at S, which touches this disc, and back to the battery.
x
Fig. ”

“ Fig. 56
One end of each coil is attached to a common return wire C, the other end going to the push P. When P is depressed, the circuit of any drop is through M along C through bell, battery and up common battery wire W back to other contact of push P. Depressing any push does not therefore affect any other drop but the one controlled by it. ”

“ This system does away with large batteries and is very economical of wire. The current needed for the relay is very small, whereas in a direct system of any size, the current and voltage to ring a number of bells located at wide intervals would be prohibitive.
The reference letters are as follows: AA are the alarm bells, BB the break-glass alarm boxes, C is the annunciator bell, D is the relay which remains closed when an alarm comes in keeping the bells constantly ringing until shut off. E is a resistance coil and F is the battery. ”

“ Then see that the circuit wires are firmly clamped in the terminals and no dirt or corrosion on the connections.
Next examine the push button and see that the wire connections at the springs are perfect.
If there is no movement of the bell at all when the push is pressed in, take a pocket knife or screw driver, and touch the blade across the push springs. If there is current flowing sparks will be seen when the blade breaks contact between37 the springs. If there are no sparks, detach the wires from the bell and twist the bare ends together. ”

“ Molten wax, or a suitable composition, is then poured on top of the contents of the cell to seal it up and prevent the evaporation of the fluid. A terminal on the carbon rod and another on the zinc case complete the cell.
Fig. 4
The voltage of both the Leclanche and the dry cell is about 1.45, when it goes below this it indicates that the cell is worked out.
The two cells described are known as open-circuit cells and are only intended for intermittent working.
When a current is needed for a long period at a time a closed circuit cell should be used, such as the gravity Daniell cell. ”

“ On examining many electric bells it will be noted that only one binding post is insulated from the frame when the latter is of iron (Fig. 34) . As the armature spring S is in electrical connection with the frame F by reason of its metal screws and support, the circuit may run from the insulated post U to the magnet coils, thence through the insulated contact screw C through the armature spring (when it is making contact) and through the frame to the uninsulated post I.
Fig. ”

“ In Fig. 45 is a diagram of a closed-circuit burglar alarm, C a cell of gravity battery, R a48 relay, F the fixed contact and M the movable contact of the spring, S a stud projecting through the base of the spring and pushed in by the closed door.
When the door is closed, S being pushed in, the circuit of C, R, F and M is closed. The magnets of the relay hold the armature arm A forward against a hard rubber contact. But when S is released, the relay circuit is opened, R loses its power and A flies back, making contact, and throwing in circuit bell B and battery L.
Fig. ”

“ First short circuit the push springs by inserting a knife blade or piece of wire so as to touch both of them. Then touch the two wires at the bell, one to each side wire coming from the magnet coils. If current is up to the bell and the coils are all right, a single stroke should result.
Replace the wires in the binding posts, clean the platinum on both contact screw and armature spring and try the adjustment. Troubles in the bell will be mostly similar to those before mentioned. ”

“ But it does not stop it entirely, as will be seen if the Leclanche cell is kept working above its capacity. Then the hydrogen is generated too fast for the manganese to destroy it, and the cell3 ceases to work. In this case a rest will often restore the cell to its former power.
Cells which have been almost unable to make a bell give even a single tap have been found good again when allowed to remain at rest over night.
In setting up a battery cell no liquid should be splashed on the brass terminals or corrosion will take place. ”

“ Upon the care with which a joint is made much depends, a loose or poorly made joint will offer much resistance to the current.
The correct way to start a joint in annunciator, or office, wire is shown in Fig. 22. About three inches of each wire to be joined is bared of its insulation and scraped bright. The ends are then25 bent at right angles to each other, hooked together and one end firmly twisted around the other, as shown in Fig. 23. Any projecting pieces are cut off, and the joints should then be soldered to prevent corrosion.
Fig. 22
Fig. ”

“ Being screwed up near the door pull, a wire is run from the latter and fastened to lever L. When the pull is drawn out the lever L turns on a pivot and a projection presses the insulated spring S against the metal base B. The circuit of the bell and battery being thus closed, the bell rings.
Fig. 21 Indicating Push Button. ”

“ Fig. 10 shows the ordinary form of gong. Fig. 11, a tea gong; Fig. 12, a cow gong; and Fig. 13, a sleigh bell.
Fig. 10 Fig. 11 Fig. 12 Fig. 13
A coil of steel wire is also used, as in Fig. 14, which on being struck by the hammer gives a pleasant but not loud tone.
Fig. 14 The Buzzer.
The buzzer is the mechanism of a vibrating bell less the hammer and gong. As the armature vibrates it makes a buzzing noise which does not carry as far as the sound from a struck gong. ”

“ When running along a skirting, the wires may often be pushed out of sight between it and the floor. Do not attempt to draw the wires too tight or the changes of the weather may break the wires when the woodwork shrinks or swells. ”

“ Now connect up the push, baring an inch or so of each wire, push them through the holes provided in the push base, screw down the push base and clamp the wires under the washers through which the connection screws run. Do this neatly, be sure the ends of the wires do not stick out, cut off what is left free of the bared ends. Then connect the battery to the wire from the push and the wire from the bell. The last thing is to scrape and fasten the bell wires to the bell binding posts. Do this so that they cannot come loose and that they make good contact.
29
Fig. ”

“ A high screeching noise from the armature vibrating too rapidly but with too little play, may be from excessive battery power or the contact screw being too far forward. The former will generally be detected by the violent sparking as well as the rapid vibration.
In very cheap bells the platinum contacts may be replaced by German silver or some other metal.
Platinum is necessary because the sparking would soon corrode other metals, but it is very36 expensive. To test for platinum put a tiny drop of nitric acid on the suspected metal. If bubbles or smoke appear it is not platinum. ”