CHAPTER XLII
SIGN FLASHERS
The devices used for giving the flashing and changeable effects to electric lights in any form are called "flashers." The mechanism may be constructed to flash a sign by spelling the words out, one letter at a time, flashing border lights around a window, changing colors in glass signs, or in fact in any way to attract the eye.
There are two advantages in favor of using a flasher: 1, it causes the passerby to look at the sign, and 2, reduces the cost of electricity, because the lamps are switched off periodically.
There are numerous kinds of flasher, and they may be classified, according to construction of the switch contacts, as:
1. Carbon type; 2. Brush type; 3. Knife type.
Again, with respect to operation or the electrical effects, they may be classified as
1. Simple on and off flashers; 2. High speed flashers; 3. Lightning flashers; 4. Script breakers; 5. Chaser flashers; 6. Thermo flashers; 7. Carriage calls; 8. Talking signs; 9. Electric clocks.
=Carbon Flashers.=—In this type of flasher, carbon breaks are provided, that is, the arc which is formed when the circuit is broken, falls on carbon, while metal switches are provided to carry the load. Thus the carbon gets the arc which prevents the switches burning, while the switches carry the load to prevent the carbons becoming heated and disintegrated. The carbons must be adjusted occasionally according to the load they are carrying. Carbon machines are made either double, triple, or series break.
=Brush Flashers.=—These machines are provided with brush contacts. These bear on cams constituting a drum, and they are usually made of several strips of copper. Brush flashers are generally used for spelling out signs one letter at a time, or work of a similar nature.
=Knife Flashers.=—This type of construction is cheaper than the carbon type. The switches are of the knife type with metal contacts. One manufacturer states that it is not advisable to build knife flashers for more than 15 amperes per double pole switch, as they cannot be depended upon to break a greater load for any length of time.
=Simple On and Off Flashers.=—These are used for flashing whole signs or heavy loads on and off. A flasher of this type consists essentially of a revolving double pole switch with reducing gear and connection to a small motor for operating same.
The machine may have only one switch or any number of switches. The connection to motor may be by belt or chain, or the motor may be directly connected to the worm gear.
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=Flash System of Gas Lighting=—This system for simultaneously lighting a large number of gas burners, is used in large halls, churches, theatres, etc. Two sparking points, each insulated one from the other and from the burner, are arranged at each burner, so that a spark between the points passes through the jet of gas and ignites it. A number of sparking points and the secondary of an induction coil are connected in series. When the circuit through the primary of the induction coil is closed, sufficient pressure is induced in the secondary to cause sparks to jump across every jet in the series. Since the voltage is high, the wires must be installed with great precaution. The wire should be enclosed in glass tubing wherever it comes within less than 1¼ in. from the gas piping, except where purposely grounded.
=High Speed Flashers.=—Machines of this type are used for giving what is generally known as _high speed effects_, such as fountains, water, steam, smoke and fire effects, whirling borders, revolving wheels and work of a similar nature.
=Lightning Flashers.=—These machines are for giving the appearance of a streak of lightning going across a display. There is very little expense attached to their operation, because not more than two-thirds of the lamps are turned on at one time, and this number for only about one-sixth of the time, as compared with the sign burning steadily.
Lightning strokes can be utilized in various ways, either alone or with other advertising pieces. Alone they can be placed along a cornice, across the front of a building, up and down the corners leading to a doorway, etc. They can be used in the center of a sign with letters above and below. In this case, it is best to alternate the stroke with the letters, that is, flash the wording on and then off. As soon as it goes out, the stroke flies across in the darkness, then the wording comes up again, say six times a minute.
In the case of a sign already in use, on the front of a building or over the sidewalk, a stroke can be placed leading to the sign from any point above. The flash goes down and when it hits the sign the latter lights up, holds a few seconds, goes out, and repeats about four times a minute.
Lightning flashes are not usually constructed for heavy loads, the one shown in fig. 1,025 being designed for two amperes.
=Script Breakers.=—Flashers of this type are used for breaking large script signs, one socket at a time; that is, each lamp is lighted one after another until all are on. After a few seconds they all go out simultaneously and repeat. This gives the appearance of an invisible hand, writing the name in the darkness, and is very effective. The result can be accomplished only with script, and to get the proper effect the smallest letter in a sign should be not less than two feet high; the larger the letter, the better the effect.
Script breakers are also used for fancy border signs of other kinds, and in order to produce these results, it is necessary that the return wire of every lamp go back to the flashers independently, which means a wire for each lamp.
=Chaser Flashers.=—This class of flasher is designed to operate signs whose lamps are arranged to give the effect of snakes chasing each other around the border. This peculiar effect is produced by having a separate wire and a separate switch on the flasher for each two lamps in the border, and the mechanism so arranged that when the tenth lamp is lighted (assuming the snake to be ten lamps long) the first lamp goes out; when the eleventh is lighted, the second goes out, etc., progressing in this way around the entire border.
In operation, the lamps are turned on and off so rapidly that it produces the effect of snakes.
It is not advisable to build these signs small nor cheaply, as in order to produce the desired effect, the curved path taken by the snake should cover at least 10 inches width, which would mean a total of 20 inches lateral space for the snake in addition to the electric letters in the center. In order to get the proper effect, the sign should be at least ten feet long.
=Ques. Why are chaser signs expensive?=
Ans. It is on account of the care required in their construction, large amount of wiring necessary and large flasher required.
A sign four by ten feet outside dimensions, would require in the neighborhood of 150 lamps in the border alone on each side. This would require a flasher with 75 switches and about 82 wires to run between the sign and flasher.
=Ques. How are chaser signs worked?=
Ans. There are several ways of operating these signs. The border is generally working continuously, while the center can be flashed or not, as may be desired. Flashing the wording reduces the current expense, which offsets in a measure the extra cost of the sign.
The border, although working continuously consumes very little current.
=Ques. What is the relative cost of a one snake sign as compared with a two snake sign?=
Ans. One snake running around the border would cost twice as much for flasher and wiring as a two snake flasher.
Three snakes would cost about 25 per cent. less for flasher and wiring than for two snakes. The smaller the number of snakes travelling around the border at one time, the greater the expense of wiring and flasher.
=Ques. How many snakes should there be for best effect?=
Ans. Two is considered best. Three may be used on some signs, but more than four would, in most cases, so crowd them as to spoil the effect entirely.
=Thermo Flashers.=—These flashers work on the thermo or heat expansion principle, that is, the movement of the contact points of the flasher necessary to open and close the circuit is obtained automatically by the alternate heating and cooling of the metal of the flasher, which causes it to expand and contract.
=Carriage Calls.=—These are used to avoid the confusion and noise at the theatre, club house or department store when vehicles are called by a megaphone.
The call itself consists of two or more sheet steel boxes, one of which is shown in fig. 1,032, with incandescent lamps arranged in metal compartments in such order that any number may be produced by lighting the proper lamps.
The flashing of the number is controlled by a keyboard or switch which may be placed in any convenient location. When the switch and call are connected together, any numeral may be flashed by pressing the corresponding key. The numeral automatically remains lighted until the releasing button is pressed.
=Talking Signs.=—This type of electric sign automatically flashes out in brilliant letters, different phrases or announcements. These are flashed out repeatedly and continuously during the operation of the sign and the changes follow each other without intermission of darkness.
The talking sign consists of any desired number of monograms or units, in each of which any letter or figure can be formed by lighting certain combinations of incandescent lamps. A unit is shown in fig. 1,032. The lamps are controlled by a simple mechanical arrangement operated by a small motor. Any reading matter can be flashed by properly setting the mechanism.
The flashing of the letters or numerals in the monogram is controlled by commutators, one commutator being required for each monogram, except for a double faced sign where the corresponding monogram on each side is controlled by the same commutator.