The Blitzen Receiving Set was an easy-to-use crystal receiver, which had been introduced by the Clapp-Eastham company earlier in the year.
The American Jeweler, October, 1912, pages 409-411:
WIRELESS TIME SIGNAL APPARATUS.
ITS INSTALLATION, OPERATION AND COST.
BY T. STANLEY CURTIS.
The completion of Uncle Sam's powerful new wireless station at Arlington, Va., will mark an achievement of great importance to retail jewelers throughout the country. It will mean that daily time signals, direct from the Naval Observatory at Washington, D. C., will be available to jewelers who install the simple and comparatively inexpensive instruments which are required for the receipt of signals through the ether. This service is already in use in the vicinity of the chain of government wireless stations extending along the entire Atlantic coast and the signals are readily received by stations within a few hundred miles of these installations. The gigantic station at Arlington, however, supplemented by the Atlantic and Pacific coast stations, should make the service country-wide in extent.
The great possibilities of this system have awakened a lively interest among jewelers in the necessary apparatus for small receiving stations and it will be the aim of the author to present a brief outline of the various instruments together with hints in regard to their installation and use. Technical details will be avoided and the theoretical touch in the following paragraph is included only in the hope that it will be conducive to a more thorough understanding of the principles which govern the operation of the apparatus.
Perhaps the simplest possible analogy to the transmission of wireless signals is that of a perfectly smooth sheet of water into the center of which a pebble is dropped. Little ripples or waves are propagated at the point where the pebble strikes the water, extending in concentric and constantly widening circles, until they are spent either in the distance or against the sides of the water container. The wireless "waves" are vibrations of the ether set up at the transmitting aerial at every pressure of the key, and extending in all directions just as the water ripples extended from the pebble. These waves or vibrations are similar in nature to the waves of light and heat although of vastly different frequency. The retina of the eye is sensitive to light waves; our sense of touch responds to the slower vibrations of the ether and our nerves record the sensation we call heat. We cannot see the waves of light or heat but the human organism is fitted with receiving apparatus which responds to these waves so that our nerves may transmit their message to the brain. It therefore follows that, in order to make the wireless waves available for the transmission of signals, we must provide some form of receiver which will catch the vibrations and then so change them in form that they will make an impression on our senses.
The function of the modern wireless receiver is to collect the electromagnetic waves as they come through space and to pass the minute alternating electric current through a device which rectifies it into a pulsating direct current which, in turn, acts upon a telephone receiver. The signals are heard in the telephone as a series of dots and dashes, various groups corresponding to the letters of the alphabet.
The receipt of messages, via wireless, of course necessitates a knowledge of the telegraphic codes. The jeweler, however, need not take the time to learn the codes as the time signals are sent in a clearly defined series of dots and dashes which are readily recognized once they are heard.
Receiving outfits may be obtained in either of two forms, viz., a complete set of instruments mounted in a single cabinet or the separate instruments mounted on individual bases of marble and wood. The cost and working qualities are identical in the two types and each has its advantages. The cabinet set is neat and compact and all necessary connections are made within the case so that there is practically no chance for an error in the installation of the set. The separate instruments present a rather more imposing appearance and their use affords the jeweler an opportunity to work in a little publicity by arranging the instruments attractively on a table in his store with an appropriate announcement hanging close at hand. This idea may readily be extended to a window display to first call attention to the wireless time signal service. Details of such a plan will suggest themselves to the enterprising retailer and suffice it to say that the mere mention of "wireless" in a store or show window is sufficient to draw a crowd at the present day.
The half-tone, Fig. 1, gives an idea of the appearance of a complete set mounted in the cabinet. The remaining illustrations, Figs. 2 to 6, inclusive, show the separate instruments and for the benefit of those who may wish to use this type of outfit, an explanation of the necessary connections will be given.
The connecting wires may be of silk covered incandescent lamp cord if appearance is an object. This "cord," which is really a flexible stranded copper conductor, may be purchased for a few cents a yard from any electrical supply dealer or from the firm selling the wireless apparatus.
The reader's attention is directed to the instrument shown at Fig. 2. The function of this device, called a "tuner," is to "tune in" the station from which it is desired to receive and to eliminate the signals from other stations which happen to be operating at the same time. There are four binding posts or terminals under which the connecting wires are to be fastened and two of these terminals are marked A and G respectively. To these the "aerial" and "ground" wires are to be fastened but more of this later. The use of the second pair of terminals will be seen on reference to Fig. 7 which shows the method of connecting the separate instruments.
The connecting wires should be stripped of their insulation for an inch at the point where the connection is made and the bare copper firmly clamped under the nut of the binding post. As the drawing indicates, a wire is run from a post of the tuner to the variable condenser and thence to the detector. From the other post of the detector a second wire goes to the fixed condenser. From the remaining post of the fixed condenser a third wire passes to the variable condenser and from there to the second post of the tuner. The tips of the cords fastened to the telephone receivers are secured to the binding posts of the fixed condenser as indicated. This completes the wiring of the separate instruments which are now electrically connected just as they are in the cabinet shown in Fig. 1 and having but two unused terminals, A and G, on the tuner, which correspond to those bearing the same letters on the cabinet.
The location of the apparatus is optional with the user and almost any convenient portion of the store may be utilized. The wires leading from the aerial or antenna on the roof to the instruments and from the instruments to ground should be standard No. 14 rubber covered electric light wire run on single porcelain knobs. From the antenna the wire may be run down the outside of the building and brought in through a porcelain tube in a convenient window casing, or, better still, through a hole drilled in the center of the window pane. This wire is connected to post "A" on the set. The "ground" wire is to be run from post "G" to the nearest water pipe which affords a most effective ground connection. When the set is not in use, the switch shown in Fig. 7 is to be closed to protect the instruments from lightning during a thunder storm.
One feature of the installation may appear to present some difficulties to the layman and that is the aerial or antenna which serves to intercept the wireless waves as they pass through the ether. The prospective user is advised to observe some local amateur station, a number of which are to be found in nearly every town in the country.
The appended sketch, Fig. 8, illustrates a simple and efficient form of antenna. The masts may be of wood, suitably guyed to strengthen them. The "flat top" aerial, Fig. 8, is perhaps the most popular and it is sometimes suspended between adjacent buildings or between masts on the one roof. The chief requirements are that the aerial be as long and as high as possible, keeping in mind the fact that the strength of the signals and therefore the receiving radius is largely in proportion to these two factors. While it is possible to receive from a single wire a few feet long suspended in the air, still the range would be comparatively small.
The insulators mentioned in the sketches are made for the purpose from a composition called "electrose." The dimensions given are merely suggestions and local conditions would necessitate changes in many cases. The proportion of height to length is usually about one to three in an aerial of the flat top type.
Assuming that the instruments and aerial have been installed and all connections made, let us turn our attention to the adjustment and operation of the set. The first step will be to adjust the detector by means of the metal point resting on the sensitive mineral. All points of this mineral are not sensitive (or equally so) and it will be necessary to move the point around from place to place on the crystal until clicks or buzzes are heard in the telephone receivers which are, of course, to be in position at the operator's ears while adjustments are being made. A most convenient testing device is that shown at Fig. 9. An ordinary electric buzzer is connected to a dry battery with a switch in the circuit as shown. From one binding post of the buzzer a wire is run to the "A" post on the tuner and when the buzzer is operated, a false signal will be produced in the telephone receivers. This signal will be loudest when the detector is perfectly adjusted and when adjustment is attained, the buzzer switch should be opened.
It is probable that signals, consisting of a series of dots and dashes, will now be heard in the telephone receivers. The operator will, no doubt, be able to distinguish one station from another by the difference in the tone of their respective sparks, even though he be in ignorance of the codes. He will find that by turning first one and then another of the concentric hard rubber handles of the tuner, that he can strengthen the signals of one station and, in most cases, entirely eliminate those of the other stations. If the manipulation of these handles does not cut out the undesired signals, the handle of the variable condenser may be turned slightly and the effect noted. A few minutes' practice will mean more to the user than many pages of instruction and it will be found comparatively easy to "tune" in or out the stations as desired.
A few words concerning the cost of the instruments may not be amiss. The complete set of instruments illustrated, either mounted in the cabinet or separately, may be purchased for $33.00 and the wire knobs, mast for antenna, etc., will cost but a few dollars extra. The apparatus requires no electric current, other than that coming through the aerial for its operation and there are, therefore, no maintenance charges to be met. The first cost is the total one.
Aside from the chief object of the set, that of receiving time signals, the owner will experience that inevitable fascination in the receipt of the signals through the ether and will, sooner or later, make himself familiar with the telegraphic codes so that ne may take messages at spare moments.
The manufacturers are always glad to supply any special information in connection with the installation of a set and it is suggested that prospective users write, giving particulars regarding their buildings. These items should include the height, length and width of roof and the general construction of building.
The American Jeweler, September, 1912, page 353:
This publicity photograph from the cover of the September, 1912 American Jeweler appears to be a Blitzen Receiving Set in operation: