Detector

“ I fancy some of your radio experts would gape if they were permitted to see my wave meter. I believe it would cause some excitement in the laboratories of Lodge or Marconi. I—Proctor—I measured these waves which, of course, means that I found a detector for them. Our friend DeForest thinks that he has a monopoly on ultra-sensitive detectors. Proctor's detector is to the audion what a stop watch is to a wheel barrow! ”

“ He looked into my eyes and read the question I was too weak to speak aloud.
"No," he said, "we didn't figure out Baxter's extractor. But we do have a successful detector, and all we have to do now is use it—then hang a tin can or an old ketchup bottle on each speck of metal for a marker. Yeah, the country's going to be cluttered up like a hanging garbage dump for a long time, but if you can see 'em you can dodge 'em."
A detector? Why, they'd have to equip every person in the country with one! ”

“ As Commodore Theodore Wilson eyed the infrawave detector presentation on the dome of the detector ship, he groaned. The presentation of targets was stronger now. At the apex of the dome was the lifeship, its response waxing and waning, but always strong enough to stay visible even at its lowest ebb. ”

“ Another form of detector is the "electrolytic" which consists of a very fine platinum wire about one ten-thousandth of an inch in diameter, which dips into a platinum cup filled with nitric acid. When the invisible electro-magnetic waves impinge upon the wires of the receiving station, and cause electrical surges to take place in those wires, they in turn affect the detector, giving an exact reproduction of the note of the transmitting spark at the distant station. ”

“ The detector was simple, though the tuning had to be precise. A dish-shaped antenna pulled in the signal for the delicately balanced detector. There was a sharp fall-off on both sides of the input so direction could be precisely determined. The resulting signal was fed to an amplifier stage. ”

“ The detector, sometimes known to users of the radio as a “cat’s whisker,” is a thin wire with a point attached to it, extending from the sounding posts to a piece of galena or silicon. This detector is used for this reason: The voice waves that are sent out through a radio transmitter are too faint to be heard by the human ear unaided by a mechanical apparatus. ”

“ A fourth class of electric wave detector comprises the thermal detectors which operate in virtue of the fact that electric oscillations create heat in a fine wire through which they pass. One form such a detector takes is the bolometer. If a loop of very fine platinum wire, prepared by the Wollaston process, is included in an exhausted glass bulb like an incandescent lamp, then when electric oscillations are sent through it its resistance is increased. ”

“ All you need for this set are: (1) a crystal detector, (2) a tuning coil and (3) an earphone. You can make a crystal detector out of a couple of binding posts, a bit of galena and a piece of brass wire, or, better, you can buy one all ready to use for 50 cents.
The Crystal Detector.--This is known as the Rasco baby detector and it is made and sold by the Radio Specialty Company, 96 Park Place, New York City. It is shown in Fig. 96. ”

“ After the instruments are connected, place a piece of galena or silicon in the cup of the detector and bring the wire down on it. Then move the sliders on the tuning coil or loose coupler and adjust the detector until you can hear a message buzzing in the telephones. It may require a little patience and practice, but if you persist you will soon learn how to adjust the apparatus so as to receive the signals loudly and clearly with very little trouble. ”

“ The answer, from a technological planet, was a technological one. Build a space fleet and equip it with some sort of a detection-fire network.
This was done in record time. The Attison Detector was developed, a cross between radar and the electroencephalograph. Any alteration from the typical human brain wave pattern of the occupants of a Detector-equipped ship would boost the indicator around the dial. Even a bad dream or a case of indigestion would jar it.
It seemed probable that any attempt to take over a human mind would disturb something. ”

“ If the two sides of the spark gap are connected with the two pairs of quadrants of a very delicate electrometer, the needle of which is connected with one pair of quadrants, there will be a deflection of the electrometer when the detector is struck by electric waves. A very efficient detector is that invented by E. Rutherford (Trans. Roy. Soc. A. 1897, 189, p. 1) ; it consists of a bundle of fine iron wires magnetized to saturation and placed inside a small magnetizing coil, through which the electric waves cause rapidly alternating currents to pass which demagnetize the soft iron. ”

“ If is the distance of the detector from the reflector when the sparks are brightest, and the velocity of propagation of electromagnetic disturbance, then where is an integer and the time of vibration of the detector, the distance between two spark maxima will be and the places where the sparks are a minimum will be midway between the maxima. ”

“ The receiving apparatus consists of some form of detector and a telephone receiver and battery. The usual form of detector employed is the electrolytic. The currents generated in the receiving aerial by the incoming waves vary in amplitude with those of the transmitting aerial, and, being in perfect accordance with the vibrations conveyed into the transmitter, cause the detector and telephone transmitter to reproduce the speech perfectly. ”

“ He must also see that his detector is adjusted to its greatest degree of sensibility and his tuner to the proper wave length. If your station happens to be near another, or if you are one of a group of ships and other vessels near yours are sending, you must watch out and either weaken the coupling of your detector or open your switch and cut it out altogether when those around you are using powerful currents for transmission ”

“ The reason a vacuum tube detector is more sensitive than a crystal detector is because while the latter merely rectifies the oscillating current that surges in the receiving circuits, the former acts as an amplifier at the same time. ”

“ But of course they didn't have our detector screens nor our armament. According to the observatories we're in clear ether, but I wouldn't trust them from Tellus to Luna. You have given the new orders, of course?"
"Yes, sir. Detectors full out, all three courses of defensive screen on the trips, projectors manned, suits on the hooks. Every object detected in the outer space to be investigated immediately--if vessels, they are to be warned to stay beyond extreme range. Anything entering the fourth zone is to be rayed." ”

“ His only hope of escaping detection was his knowledge that the negative-detector, developed in the Orionad for use against sub-ships was less sensitive as to range than the positive-detector. The establishment of negative evidence is never conclusive. And his souped-up detector would outrange any but another souped-up job.
So Guy coasted for days, which at five thousand miles took him far, far beyond the orbit of Pluto. ”

“ Taking out a key and opening the detector, the keeper said, “I thought you might like to see [40] this. There, I have put this round card in the detector. You see it is marked off into hours, and ten minutes, and five minutes, and is called the dial. The patrol takes it with him, and at the end of his beat he puts a key in that hole you see, and gives the key a turn. A kind of punch, stamped like a die, is forced down on the dial. In the morning, I open the detector, and there is the dial that tells if he has done his duty. ”

“ This time the magnetic detectors showed not the slightest deflection. Slowly they steamed back and forth twice over the marked spot, listening as well as watching the magnetic detector, but not a sign or sound was recorded. Then they steamed at fifteen knots on a “retiring search curve” like a watch-spring around the lighted float, listening intently, till they had covered a circle with a radius of a mile and a half, but no trace was found, magnetic or audible, of the submarine. ”

“ When used as a receiver for wireless telegraphy Marconi inserted the oscillation coil of this detector in between the earth and a receiving antenna, and this produced one of the most sensitive receivers yet made for wireless telegraphy. Other forms of magnetic detector have been devised by J. A. Fleming, [34] L. H. Walter and J. A. Ewing, [35] H. T. Simon and M. Reich, [36] R. A. Fessenden [37] and others.
A third class of electric wave detector depends upon the power of electric oscillations to annul the electrolytic polarization of electrodes of small surface immersed in an electrolyte. ”

“ The interposition of a circular structure like that of a disc of rolled paper on the path of polarised electric radiation is found to project a dark cross into space, the outline of which can be definitely found by means of the exploring detector. ”

“ Time will not permit me to discuss all the different forms of electric-wave detector which have been invented. For our present purposes we must limit ourselves to the description of one plan, which depends on the remarkable fact that finely powdered dry metal or metallic filings are non-conductors of the electric current until they are subjected to an electromotive force exceeding a certain value, when the metallic filings at once pass into a conductive condition. ”

“ Such apparatus is essentially appurtenant to large instruments only, say of not less than 12′′ aperture and preferably much more. The eye is enormously more sensitive as a detector of radiant energy than any device of human contrivance, and thus small telescopes can be well used for visual photometry, the bigger instruments having then merely the advantage of reaching fainter stars. ”

“ He is always supposed to. The detector's repetition-rate is about one every ten seconds, permitting ranges up to a million miles. The close-in detector runs one per second, and Black Morgan comes in from maximum range to close-in range between pulses. He hits once or twice on the close-in range—all of which gives definite evidence that he exceeds the speed of light. And he is instantly maneuverable! So he comes up behind you at a thousand times your velocity and slows down to match you in microseconds. ”

“ Those crystals magnify sounds when they’re touched or vibrated or when there’s a vibration or jar to the thing they’re resting on. Gosh! I believe I know our trouble.”
“Well, what is it?” demanded Frank.
“Why, we’ve got this rigged up for a detector—the way they did for submarines—and we do get the noises which was what they wanted when locating a sub, but we don’t get the words. ”

“ The pulse-height analyzer is a device that sorts electrical impulses from the detector according to the energy of the gamma rays causing the impulses. The screen displays the gamma-ray spectrum and the electric typewriter automatically types out the data collected when the measurement is complete. ”

“ Although there may be no sharp and defined critical electromotive force, yet, nevertheless, as a matter of fact, if the electromotive force applied exceeds a certain value, then the detector passes suddenly from one state of conductivity to another. ”

“ Astatic Current Detector. Fig. 86. The ordinary magnetic needle points to the north quite strongly. It is evident, then, that this pointing-power must be overcome by the magnetic field around the coil of wire, before the needle can be forced from the N and S line. Very weak currents will not visibly move the magnetic [Pg 83] needle in the detectors so far described. You should remember that no action will take place unless the magnetic field around the magnetic needle is acted upon by that around the coil. ”

“ As electricity cannot be seen by the human eye, some mechanism must be made which will reveal its movements.
The Detector.—It has been shown in the preceding chapter that a current of electricity passing through a wire will cause a current to pass through a parallel wire, if the two wires are placed close together, but not actually in contact with each other. An instrument which reveals this condition is called a galvanometer. It not only detects the presence of a current, but it shows the direction of its flow. ”

“ Their scientists cannot direct nor control any ray not propagated through ether, but they can detect one such frequency or band of frequencies which they call 'infra-rays' and which are probably the fifth-order rays, since they lie in the first level below the ether. The detector proper is a type of lamp, which gives a blue light at the ordinary intensity of such rays as would come from space or from an ordinary power plant, but gives a red light under strong excitation. ”

“ I used six wires forming three metallic circuits and influencing three needles. I worked out every possible permutation and practical combination of the signals given by the three needles, and I thus obtained an alphabet of twenty-six signals. I had invented the instrument which I called the detector; by means of which injuries to the wires, whether from water, fracture, or contact, are readily traced; an instrument which, in practice, is never out of my hand, and without which the electric telegraph would be impracticable. ”

“ The Crystaloi has a great advantage over other Detectors inasmuch as there are several fine, light metal points in contact with a sensitive mineral instead of the single point which most Detectors have. The Detector is so compactly made that it cannot get out of adjustment and it never loses it’s sensitiveness. ”