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Phone: HO 7. Western Marion Gillham Rd. Washington 6, D. Provides full broadband amplification covering low and high VHF channels. May also be used as FM -TV coupler. Improve TV reception today on 1, 2 or more TV sets with a single antenna. Available at parts distributors. In Canada: Telequipment Mfg. Export: Morhan Export Corp. Interest is increasing on the part of industry in young EE's as shown in the number of interviews conducted on the Lehigh campus. This year there were interviews for the 40 graduates; last year's 44 had only Over 1, transmitting stations and more than 30 million sets are in use outside this country, compared with stations and over 50 million receivers in the US.
Biggest increases were in Italy, West Germany, Japan, Russia and France, but England and Canada still led the other countries in total sets and stations. Amplifiers in the -foot tower being put up at Dugeness, Kent, England, use only 3 -kw of power to drive the speakers. Three different frequency tones are used simultaneously, making an alarm which can be heard 8 miles out to sea.
The new lighthouse will also have a small xenon arc discharge beacon about the size of a standard -watt bulb. It'll produce over half a. The tower can run unattended. It has an electronic fog- detection system which sets the foghorn into action when a ray of light beamed into the atmosphere is reflected into a photocell, and a dawn- and -dusk sensing setup. This latest fuel cell was demonstrated by Allis -Chalmers in Milwaukee. Propane, readily available from natural gas and crude oil, reacts in the fuel cell with an electrolyte to create dc.
Other fuel cells using hydrogen and oxygen have been described in this magazine.
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This particular model is made up of 1, individual fuel cells banked in four groups to allow various combinations of voltage and current. They create up to 20 horsepower in this tractor. The attack on fuel cells is through finding new catalysts to aid the reaction of the fuel with the electrolyte. Allis- Chalmers won't say what their catalyst is.
In at least one other fuel cell the catalyst is platinum. Our new plan opens the doors of Radio -Television wide to every ambitious man who is ready to act at once! Perhaps you've thought about entering this interesting, top paying field, but lack of ready money held you back. No, the explanation is simple!
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A new patented spring clip mounting gives improved resistance to shock and vibration plus improved heat dissipation. Always use Mallory FP capacitors The etched cathode FP offers increased cathode surface that prevents loss of capacitance. What's more, you can use the FP with assurance in today's tightest, hottest chassis. The FP is TC Tubular Electrolytics -now in handy new twin pack with the same high quality and performance characteristics. Try the new FP capacitor for yourself. See how it stops expensive, time-consuming callbacks. Your Mallory distributor has them Mallory GEMS-five tubular capacitors in easy -to -use dispenser: best bet for outstanding service in buffer, by -pass or coupling applications.
Registered trade mark of Radio Materials Company, a division of P. Sta -Loc' -New design enables your distributor to custom build the exact replacement you need in just 30 seconds, eliminates waiting for out -ofstock controls. Turner may have confused some readers with his explanation of the operation of "Electrostrictive Ceramics" September, through his handling of the voltage, current, power and energy relations involved.
It might appear to some from his explanation that electric devices consume less power than magnetic devices due to some fundamental properties. For example, suppose a clamped disc has a voltage applied. Current will flow from the source until it decays to zero. During this changing current flow, power is drawn. If the current is integrated over the entire time interval, we can determine the total energy required to produce an electric field in the dielectric.
Since no work is done by -the disc, the energy is stored in the electric field and may be recovered upon discharge of the capacitor disc and electrodes. Now assume that, instead of being clamped, the ceramic disc is free to flex upon application of voltage. If the disc is fixed to some object, such as a speaker cone, and moves against a restraining force, work will be accomplished and this will be reflected in an increased current or, more correctly, in an increase in the total energy.
In either case, clamped or free, after a sufficient time interval the electricfield configuration will be the same under steady -state conditions, and any force produced by the disc may be obtained from the electric field with voltage and without accompanying current flow; therefore with no further expenditure of power. The only difference between the clamped and unclamped disc is the extra energy drawn during the transient state. Now consider the magnetostrictive case in which setting up a magnetic field distorts a piece of metal, just as the ceramic disc in an electric field.
In the magnetic case, with the metal clamped, applying a current will produce a transient voltage while the field is building up. During this time power is drawn from the source. This power is stored in the magnetic field and is recoverable. Scott's Stereo Amplifier has been acclaimed "world's most versatile" by editors of all leading hi fi magazines. Like all H. Scott stereo amplifiers, it includes a third channel to give optimum realism in stereo playback and a signal for driving extension speak systems.
Other advanced features include special balancing facilities and separate tone controls on each channel to let you adjust for tonal differences in speakers and room acoustics.
It is backed by H. Scott's reputation for quality and engineering leadership. Provision for connecting two phono cartridges. Filament supply to virtually eliminate hum. Separate record scratch and rumble filters. Dual 20 watt power stages. Visual signal light panel. Stereo tape recorder output. Phase reverse switch. Third channel output. Compensation for direct connection of tape playback heads. Special switching ta use your stereo pickup on monophonic records. Play a monophonic source through both channels simultaneously. Can be used as an electronic crossover.
Completely separate Bass and Treble controls on each charnel. Special balancing circuit. Loudner compensation. Frequency Response 20 cps to 30, cps. Harmonic Distortion: 0. Noise and Hum: Hum better than 80db below full power output: noise equivalent to 10 microvolts on low level input. Accessory case extra. Scott, Inc. Rush me new catalog and complete technical specifications on all new H. Yt can be a painting, or engineering, loo. Time alone can tell which being written will be found endure. Surely, they will accepted as then today are of the books which among their fields.
They reflect the the Laboratories' telephone thinking which helps vaur Bell the scientific of nature the world's best. Dixey us the best and latest information on part numbers, etc. Couldn't do without them ". Riverside, N. Re- sult: You command public respect and acceptance which paves the way to expanded business for you Designed to help you gain deserved recognition as a reputable businessman; develop and command public respect; justify better earnings warranted by your business investment and skill; pave the way to expanded business and increased profits for you.
Low price means more sales -more profits. Flat to 15, with gradual rolloff beyond. For finest performance, replace worn needles with genuine Sonotone needles. In practice, however, there is resistance in the circuit, and voltage must be used to maintain current flow through the resistance. In addition, if work is done by the metal as the field is established, then extra power will be consumed.
If the magnetostrictive device metal does the same work the electrostrictive device ceramic does, the extra energy beyond that needed to set up the steady field will be identical neglecting secondary effects such as dielectric or hysteresis losses. It can be seen that there are two practical but not theoretical reasons why electric -field devices are sometimes superior to magnetic -field ones.
First, current sources are not available, except as derived from voltage sources, with accompanying power expenditure. Second, resistance causes loss of power. Convair Instruments A. Dear Editor: Many of your articles have been encouraging service technicians to take on more commercial gear to service. I started servicing radios back in Often customers have asked me to work on medical and factory electronics equipment.
Almost without I would never advise a radio or TV technician to try to service commercial equipment. The manufacturers prefer to send a salesman to make the service call, so he can persuade the user to replace the faulty gear with new equipment for many thousands of dollars. As an example I have been attempting for 5 months to get parts and service instructions for a NATCO -1 16 mm sound projector. I have called and even written to several companies, but with no success at all.
What would you suggest in a case like this? After every ordeal like this I swear I will never accept a service job for anything but radio, phono or TV. It is unfortunate that some companies are anxious to have their equipment serviced at the same time that many technicians are interested in servicing it, but they often can't seem to get together. This situation is improving somewhat of late, but it is still too sticky. This preamplifier does everything Mr. Ladd, the author, says it should. The wiring was easy. I recommend it to anyone interested in an inexpensive preamp for use with mikes.
Thank you. Flushing, N. It is a good value considered purely on its own merits, and a better one when its price is considered as well. Provides 28W monophonically. Identical Williamson -type, push -pull EL84 power amplifiers. Includes cover. HF85 Stereo Preamplifier is - sensitivity; precision eye- tronic8 tuning. Includes covers and F. Distortion borders on unmeasurable even at high output leves. Switched -in loudness compensator.
Selector switch chooses mono or stereo service; 4, 8, 16, and 32 ohm speaker taps, input level controls; basic sensitivity 0. Without exaggeration, one of the very finest stereo amplifiers available regardless of price. Use with self powered stereo preamplifier -control unit HF85 recommended. Pre wired exclusive precision eye- tronic traveling tuning indicator.
Sensitivity: 1. IF bandwidth kc at 6 db points. Very low distortion. Matches HFT Selects "hi -fi" wide 20c - 9kc -3 db or weak -station narrow 20c -5kc -3 db bandpass. HF12 Mono Integrated Amplifier provides complete "front -end" facilities and true high fidelity performance.
Preferred variable crossover, feedback type tore control circuit. Highly stable Williamson -type power amplifier circuit. Power output: 12W continuous, 25W peak. Bellows- suspension, full -inch excursion 12" woofer 22 cps res. Bellows- suspension, We" excur- 3 -Way Sion, 8" woofer 45 cps res.
Jensen 8" woofer, matching Jensen compression- driver exponential horn tweeter. Smooth clean bass; crisp extended highs. Completely factory- built. In EICO's final test techniques, nothing is left to chance. Sensitive ua meter. Direct reading of inter -element leakage in ohms. New gear- driven rollchart. B Entirely electronic sweep circuit with accurately- biased increductor for excellent linearity.
Extremely flat RF output. Exceptional tuning accuracy. Hum and leakage eliminated. Narrow range phasing control for accurate alignment. C Ice to mc with ONE generator in 6 fund. Colpitts RF osc. Variable depth of int. Turret -mounted, slug -tuned coils for max. Fine and Coarse 3 -step RF attenuators.
RF output , uv, AF output to 10 v. Calibration without re- - moving from cabinet. Ohms: 0. Zero center. Features DC amplifiers! Flat from DC to 4. Sweep: perfectly linear 10 cps kc ext. Auto sync. Direct or cap. Prealigned RF, IF xfmrs; push -pull audio; 6" spkr. Astounding Growth of Electronics Calls for New Strategy N important government official, commenting on the chaos of electronic research, recently rebuked American research scientists for failing to make use of available Russian data.
This occurred in early October, during the Chicago meeting of the National Electronics Conference, and was described in a news report: "John C. Green offered several reasons -researchers don't want new sources of information because they are already floundering in reports; some still discount the worth of Russian data, and others simply don't know the Russian translations are available. How could it be otherwise in an industry that mushrooms at such a fantastic rate of growth that it doubles its new inventions and devices every few years?
What will the electronics field be in 10 years, 25 years, 50 years hence? Today we have millions of electronic facts available to our researchers. Soon there will be billions of facts -what then? Several times in recent years, research teams have developed "new" devices, only to find that identical ones had been in use elsewhere for a different purpose. They had been fully described in technical papers, too. Recently, full -page ads in newspapers throughout the country announced the "new" "electronic," "ventilated," "aerated" or "air- conditioned" cigarettes breakthrough in smoking.
Just how new and revolutionizing is this? In the early 's, when the present writer was a young boy in Europe, one of the most hilarious jokes went as follows: You asked a friend to lend you his cigarette -paper book -usually Riz -La Croix brand. You then proceeded to roll your own cigarette. But instead of returning his book of cigarette papers, you substituted your own. This one you had "prepared" by placing it on a metal plate, wired to the hot side of a spark coil.
The other side went to a sharp probe, which you carefully guided for 5 minutes over the cigarette book while the spark coil was "on. Now, when your victim tried to smoke his cigarette with such a "super- aerated" paper, there was no smoke forthcoming no matter how furiously he drew and puffed, simply because the paper acted as an excellent sieve. All your friend got was air and frustration! The idea was described in French and German books in the 90's, as well as in Practical Electrics, one of the writer's magazines May, , page Carefully regulat- ing the frequency of the holes along the shaft of the cigarette causes the smoker to get less smoke and more air -also less nicotine and tar.
This really gives you a cigarette with an electronic carburetor. Of course, you no longer get your money's worth in tobacco, but then -sh -h -the cancer risk is less, too. This makes everybody happy -manufacturer and consumer as well. Hurrah for electronics! Let us give cigarette manufacturers the benefit of the doubt and admit that they probably never heard of the ancient spark -coil cigarette -paper joke; which is precisely the point of this article. Useless, uncoordinated research is dogging every industry today.
Duplication of research, effort and money is the order of the day. Will it stop before all of our progress is engulfed? Only the Government is big enough to build and run such a center. It would be far larger than even the Pentagon. Nor would the information which it supplied be free -not any more free than the US Patent Office services.
Whatever information was demanded by any industry or individual would cost a statutory fee, determined by various schedules. The Center would be equipped with possibly the largest array of electronic computers in existence. Every important scientific, electronic and industrial fact would be coded and carded, cross -indexed for various industries.
All these billions of facts would be fed to the computers in such a manner that, upon inquiry, the proper information could be given, often within seconds. These facts and information would not come solely from American sources. That would defeat the whole purpose. Facts would be culled from every country of the world, because only in this manner could the Center be all- comprehensive.
The Center would have to be closely allied with the Patent Office for intimate reciprocal information of every kind -indeed each would be dependent upon the other. But industry, researchers, inventors and others would not have to waste their time any longer in useless research, when the key to their problem would be forthcoming within minutes from the Center.
To be sure, the key itself would solve no problems would state, however, where your vital information could be had. It would be an immense shortcut to all research. How long does electronic computer information -on magnetic tape and memory magnetic cores -last? Remember the Center would entrust to the computers thousands of billions of vital facts. The experts in the field assure us that magnetic Mylar tape -the tape itself and the magnetic iron oxide -will last, at the present state of the art, as least years.
It may, with improvements to come, last much longer. Magnetic cores and the magnetism impressed on them, we are informed, will probably last hundreds of years. All this need not worry anyone, because the thousands of scientists and technicians of the future National Facts Center would continuously replace old magnetic tapes and memory cores with new ones as a routine procedure. Typical delay line with lumped components.
Special tubes with very closely spaced electrodes, such as the lighthouse and pencil triodes, solve some of the problems up to 3, nie. Above this, on the transmitting end we just oscillate up a storm with bigger and better klystrons and magnetrons, and on the receiving end we heterodyne the feeble signals with a local oscillator and use a lot of if amplification.
The disadvantages of such a system are obvious. We depend on the brute force of a signal which can easily be interrupted by interfering conditions and distorted by noise, or we have to make the transmitting range so small that we can hardly miss. Traveling -wave tubes offer a new approach to the problem. How they do this is what this story is about. But to understand the tubes, we must first understand the problem we are dealing with.
Yet here we find the most important and versatile applications of communications, long -distance remote con- L l Transit -time problem The core of the trouble is transit time. It takes electrons a finite time to travel from the cathode to the plate. In the tubes in your radio or television receiver the transit time is about. The ordinary tube would long ago have ceased amplifying.
Let's see why. Here we have a triode with a negative grid bias. As we apply an input signal, the grid becomes less and less negative on the positive swing of the signal. Because of this the number of electrons in the stream from the cathode becomes greater, and we find a much denser electron population between grid and cathode than between grid and plate, because a number of the electrons haven't had time to get through the grid to the plate side yet.
Because more charges electrons are approaching the grid than are leaving, the approaching mass of electrons, slowed down by the grid still negative with respect to the cathode , imparts energy to actually does work in repelling electrons from the grid out into the external grid circuit. When the input signal passes its positive peak and start to decrease, more electrons will be between the grid and plate -leaving the grid -and electrons flow back into the grid from the external circuit. When the signal reaches a negative maximum, this it- capacitive grid current reverses itself, reaching zero well before the voltage.
In other words, we have a phase shift. The grid current leads the signal voltage, and we have a capacitive reactance in the grid circuit. Now, you know that the higher the frequency the lower the capacitive reactance becomes, so the tube draws current from the input circuit, loads it and lowers the input signal because of lowered gridcircuit impedance.
The phase shift is proportional to the frequency and the transit time. Second, we can regard the tube's dynamic plate resistance as a complex quantity, made up of the resistive characteristics of the electron stream and the interelectrode capacitance in series. This, too, decreases plate resistance at higher frequencies.
The lowered grid impedance lowers the transconductance. The amplification of the tube is the product of the transconductance and the plate resistance. Thus the amplification of the tube is very drastically reduced at these higher frequencies. This then is the transit -time problem -how to increase amplification which has been reduced because the electrons are slow. All the foregoing is pertinent to our discussion of traveling wave tubes. For they are a good practical example of the proverb "If you can't lick them, join them. First, let us look at the construction of the traveling -wave tube TWT.
At the left is an electron gun, similar to the type used in cathode -ray tubes, which is capable of producing a collimated beam of electrons in the order of ', inch in diameter. Then comes a long thin glass tube with a wire helix inside. The helix may have as many as 50 turns per inch. At the far right is the connection to the helix, and at two points on the tube we see a spiral wound outside the glass. Then, finally, at the far right there is a positive collecting electrode. Typically the whole assembly is about 12 to 15 inches long although much shorter tubes are being made experimentally and the helix is about 9 inches long.
The electron gun is not very special, except for the shape of the beam, which is of uniform thickness. There is a heater supply, an anode supply and a variable high -voltage supply for the helix. Then there are the input and output connections which, as we see, are made by the spiral around the glass and not by direct connection to anything.
How it works We talked about transit time, and we know that the electrons take a certain finite time to travel from the cathode to the collector electrode. To make use of the ability of this electron beam to impart energy to a wave, we must try to make a wave travel at about the same speed as the electrons. This is the purpose of the helix. The next logical question is, "How does the helix work? How this is done is explained later. A wave normally travels through space or along a path in a waveguide or, in the simplest terms, along a wire, with about the speed of light.
But if we wind the wire into a helix, we create capacitance between the turns, and the turns themselves are in effect inductances. Now if you know what a conventional delay line consisting of series inductances and parallel capacitors looks like see Fig. In fact, the helix is enough of a delay line to slow the wave down by a factor of maybe as much as As the slowed-down wave travels the length of the tube, we shoot the electron stream down through the center of it. Now what happens? The wave has both an electrostatic and a magnetic component.
The magnetic component isn't useful to us. In fact all it does is try to scatter the electrons and break up our nice tight stream. However, we counteract this effect. The electrostatic component is what we use. We represent the instantaneous pattern of the field due to the wave in the tube as in Fig.
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Thus some electrons will be speeded up and some slowed down, under the influence of the wave, and the beam of electrons will alter nately be made denser and less dense Fig. We have produced bunches of electrons all along the beam. By changing the relative collector voltage we can change also the average speed of the electrons, and by choosing our velocities just right we can assure that the bunches of electrons we form with the wave field are either always in a retarding or an accelerating field. Arrows pointing to the left accelerate, and to the right retard, electrons moving along the tube from left to right.
If we retard an electron or anything else , we make it give up some of its kinetic energy. This energy must go somewhere, for it cannot be lost. In our case the energy is imparted to the wave, which then becomes a little stronger each time a bunch of electrons gives it some energy. The attenuator helps keep reflected energy from traveling back down the tube in shf amplifiers. The individual units cover the 15, -me spectrum in a series of 2-to -1 frequency bands : 1,, 1,, mc, etc.
To counteract the magnetic component which tends to scatter the electron beam we use a magnetic focusing field around the tube. This can be done with a solenoid Fig. To understand this, you must grasp how a waveguide can be energized by a simple stub antenna or simply accept the fact. Actually the development of waveguides followed the use of coaxial lines, and a waveguide can be regarded as a coaxial line with the center conductor removed except at the very ends, where for purposes of putting the energy into the guide and taking it out we have left the center conductor, or something which acts like a center conductor.
This can take many forms, and it need not be parallel to the walls of the waveguide. In early traveling -wave tubes, input and output were handled by a short section of waveguide see Fig. The helix was then functioning as the abbreviated center conductor. However, as the development of wave guides progressed delivering such new concepts as the G- string and the flat printed- circuit guides , the builders of TWT's understood that an actual conventional waveguide section was not required and that a simple wire wrapped around the glass would be just as good. Essentially, this is the idea of how we get the wave in and out of the helix with the simple outside spiral.
The electrons' velocity in their long 30 journey through the helix has to be very high if they are to reach the collector electrode. By putting a high voltage on the helix, we have some control over this velocity. So by controlling the helix and collector voltage we can make the tube suitable for waves which travel at different speeds. Since a delay line acts differently upon voltages of different frequencies, in effect we have a tube which we can use for various frequencies. Actually the traveling -wave tube is a wide-band device, but it need not always be. If we make the tube too efficient, we may end up with a very- narrow -band tube.
Here's why. If we take out the wave from the helix, say in a waveguide fashion, the waveguide in turn can reflect energy into the helix. With the reflected wave traveling backward in the tube, the efficiency will be lowered a bit. However if the reflected wave reaches the other end at all, it will again be reflected, now forward, and will then be in the right phase for amplification.
The amplified, twice -reflected wave will be added to the original, and so we have positive feedback and oscillation. Tubes designed for amplification only are so designed that the reflected portion never reaches the front end again. This is done by building losses into the helix or placing an attenuator consisting of a split graphite cylinder around it.
Tubes made for oscillators use the reflection. But with the helix voltage constant, this tube will oscillate only in a narrow band of frequencies, no matter what we do to the rest of the circuit. Thus we have the apparent contradiction that we have a narrow -band device, which can be swept by changing the helix voltage over its possible range of narrow bands.
Some readers might have difficulties visualizing a "traveling" wave when there isn't anything really moving, like particles or such. I found it useful to think of a childhood game played with a rope. If you lay the rope on the ground and vigorously wag one end up and down, the whole rope will soon be in motion, although not running away from you. Progressively the "bulges" in the rope will seem to travel forward. These traveling "bulges" illustrate the idea of a traveling wave.
It isn't going any place, it's just an amplitude which appears in different places. If a rope or, better, a violin string is wagged hard enough, particularly when it is stretched, you get the opposite or "standing" wave, which shows the same amplitude in the same place and seems to have a "bulge" which stands still. And before we forget, the backward "traveling" energy in the oscillator tube does of course cancel, in its first reflection down the tube, some of the effect of the first "forward" wave, but it is only a small percentage and more than made up for by the amplified second reflected "forward" wave.
You'll all get a kick out of seeing it light when you point at it. You can set it to remain on and use the lamp for a night light. Set it to flash about times a minute and you will have a twinkling star which is better than a night light for putting the kids to sleep. Slow the flashes down to about 60 a minute and hang it on the porch any time you're expecting guests who may not know exactly where your house is. Just tell them, "It's the one with the flasher. Whenever you want to know the time, you poke your hand in the general direction of the light and it will promptly flicker to show you where it is.
Place your finger on the bulb and you will get enough light to see your watch or clock without disturbing anyone else. When you pull your hand away, the light goes out. The mystery lamp uses about one fifth the current drawn by an electric clock and that only when it is actually lit. It is easily built and you probably have most of the necessary components in your parts box. Bottom of chassis, showing potentiometer adjustment. Do not use a metal case or chassis unless an isolation transformer is added to the circuit.
This will avoid hot -chassis dangers. The diagram shows the circuit. Use an insulated screwdriver as the potentiometer's shaft may be hot. R2 varies the circuit's resistance between 27, and , ohms. For further details see the photos. The box is painted a glossy black mystery boxes should always be black. Four rubber feet are tacked to its base to prevent bolt ends and nuts from scratching the table the box sits on.
When you are ready to use the lamp, plug it into any wall outlet and set it for the desired use. When R2 is set for minimum resistance, the lamp will glow steadily. As more resistance is added, the lamp will begin to flicker. For the mystery -lamp function, increase the resistance until the lamp just goes out. Now just point your finger at it and it will start to flicker. Touch the bulb with a couple of fingers and it will go much faster. Should the flashing fail to occur, reverse the plug at the wall outlet. END Lowdown on Traveling -Wave Tubes take a portion of the output, manage to get some of it back down the tube, and amplify this to add to the original output, and we take a portion of the now bigger output and send it back down the tube, etc.
To put it in simple terms, that's how it oscillates. What can they do? Traveling -wave tubes can have a gain of as much as 70 db. By helix voltage control, TWT oscillators can be made to oscillate over a range of 2 to 1. Thus some tubes are available which will cover the band from 1, to 2, me and so on all the way up to tubes which reach over 25, megacycles.
At present, the practical applications for TWT's are enough to keep the manufacturers quite busy. They are used first as broad -band, low -noise radio frequency amplifiers. They are used as tunable oscillators. Because of a feature which we haven't. This "grid," which is really more like a "gate," operates like the grid of a cathode -ray tube for beam modulation.
Therefore, TWT's can also be used as modulators at microwave frequencies. Telemetering, missile guidance, microwave voice communication, television program relays are present applications for the tubes. Scatter propagation, cable amplifiers for coaxial lines and radar systems are possible future applications. You can be sure that they will be playing an important part, for right now they are the only high -gain voltage amplifiers available for the microwave regions. END 31 www. Now we will see how they are used. One of the simplest devices employing solar power is a flashlight Fig.
During 5 hours' exposure to sunshine, enough energy is stored in its nickel cadmium battery to provide a minimum of 1 hour of continuous electrical power. The converter consists of 9 silicon solar cells, connected in series.
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A diode keeps the batteries from discharging during periods of no exposure to sunlight. A slightly larger converter, composed of 16 rectangular type cells, can operate a small electric fan Fig. Clocks, perpetually powered by the sun, give continuous and unlimited operation. Because of the low power drain of do clocks, a 20 -cell solar power converter is sufficient for continuous operation.
A highway flasher unit Fig. Two isolated silicon cells operate a relay that diverts charging current to the battery during daylight, and turns on a periodic flasher during darkness. This device is useful for marking highway construction work as well as airstrip emergency runways. Simple but effective broadcast type radio receivers have been designed to operate with sm ll solar power converters'". Commercial broadcast receivers are also available. The set operates either directly from the solar cells or indirectly from the nickel cadmium batteries.
Portable low -power uhf and vhf transmitters can also operate with solar -power converters. With a larger power converter and appropriate antenna system, efficient communication well beyond line -of-sight distances can be expected. Army engineers have developed a two way voice -operated FM transmitter receiver radio contained almost entirely within a combat helmet. It uses a solar power converter and miniature nickel cadmium batteries. Two banks of 38 silicon solar cells are imbedded in the top of the helmet.
These connect with the nickel-cadmium batteries to provide a power supply. The batteries, subminiature transmitter and receiver are all in the combat helmet, and weigh about 1 pound. Only the microphone is external. An eyeglass type hearing aid uses a four -cell solar power converter with a tiny nickel-cadmium battery. Bohr, Corp. The subminiature amplifier uses four transistors, and feeds a plastic earpiece.
Binaural sound is also possible. Just use two complete and independent units, one in each sidebar. High -power applications This category of solar -power application includes all devices drawing more than about 5 watts. A rural telephone type P carrier system has been powered successfully by the Bell System with a solar -power converter using silicon cells.
It provides nearly 10 watts of electrical power and is used in conjunction with 22 -volt nickel- cadmium batteries. Amplifiers and repeaters of the system are all transistor units to minimize power consumption. With this type of converter, electrical energy derived from the sun during daylight hours operates the carrier system and charges the storage batteries which take over during inclement weather and at night. A radio repeater station of the US Forest Service, atop Santiago Peak in Southern California, is powered by batteries kept charged by a cell solar power converter.
This is an un- attended, automatic repeater station using a transistor radio transmitter and receiver. Energy from the converter is transferred to the storage batteries at the rate of about watts per day. The installation needs virtually no maintenance or repair. US Army Signal Corps. Here, a -cell converter and storage batteries provide continuous power for harbor navigational aids and channel markers. Installations have also been made at other critical locations throughout the world.
Probably the most inaccessible locations where solar power converters are proving their worth are in outer space, where they function as either the primary or the only source of power in satellites. The first US satellite to be launched successfully was a 6. Distributed over its shell are 6 converters, each containing 18 silicon solar cells imbedded in ceramic cement and cushioned in a special, glassed housing Fig.
At such high altitudes, the satellite is exposed to direct sunlight more than half the time of travel around the world. Producing all necessary power for one of the radio transmitters aboard the satellite, the silicon solar cells will function indefinitely. Russian satellites have also been equipped with some type of solar power converters, but no specific technical data concerning construction and operation are available. As new and improved satellites are launched into outer space, each will probably contain a solar power converter to assure continuous electrical operation of its data transmitters.
As the physical size of satellites increases, their internal workings become more and more sophisticated, requiring additional power for operation of the various telemetering devices and radio transmitters. This requirement led to the development of ring type converters, composed of several hundred silicon cells. An even more advanced outer -space US project uses an entire missile as a satellite. Construction of one of six solar -power converters used on first US space satellite. Left to right Cover housing, 10 solar cells imbedded in cement, glass and gasket.
Ultimate in solar -power converters is ring type. These utilize nearly 3, silicon cells Fig. Although larger and more powerful than the tiny solar clusters used on early US satellites, these advanced converters are electrically similar. Without solar power, satellites would soon become ineffective as they orbit around the earth. With it, they can continue to broadcast scientific and other data concerning either outer space or the surface of the earth.
Solar power is especially important for global surveillance and reconnaissance, using television equipment to view all parts of the world while in flight, and to transmit such information to receiving sites on the earth below. Although exposed to a variety of astral elements- meteorite bombardment, cosmic dust, intense heat and cold, X -rays, and gamma rays -unless they are physically damaged, the silicon cells of solar -power converters aboard US satellites will probably outlast the radio transmitters they power as well as the satellites themselves.
Future applications Current oratories large -area extensive, experiments by leading laband manufacturers with solar cells suggest many future applications of solar power. In areas where commercial electricity is not available, houses and buildings could be literally covered with solar power converters to provide all necessary household operating electricity. Airway beacons in almost- inaccessible regions can be powered for continuous operation, as can highway markers and other aids to navigation on land, on sea or in the air. Remote weather stations, in some isolated spot or in space, could make meteorological measurements and transmit the data back to civilization by means of solar -powered and unattended radio transmitters.
Manned space stations could get enough electric power from vast clusters of solar power converters. These are but a few of the many possible, future applications of solar power. As greater amounts of electrical power can be converted from sunlight, even wider, more extensive and more exciting applications can be expected in the challenging years ahead. Future applications of solar power are almost unlimited, because of the average stability and regularity of sunlight in the temperate regions of the END world. Stable phototimer in its small case. The three ranges which fill most timing requirements are 0 to 15 seconds, 5 to 65 seconds and 0.
Tests have shown that preset timing periods are unchanged for line -voltage variations over a range of 90 to volts. Most timing circuits are dependent upon a capacitor discharging slowly through a large resistor. As the voltage across the capacitor reaches a critical value a relay circuit is actuated to give the desired timing.
The three factors which may affect the stability of timing are the time constant of the R -C timing circuit, the starting voltage of the capacitor at the beginning of the timing period and the critical voltage to which the capacitor discharges. The first cause of instability is precluded by using paper capacitors instead of electrolytics whose capacitance varies with changes of temperature, age and applied voltage.
Metallized capacitors can be used even though their change of capacitance with age is larger than that of the paper type. The other two factors affecting stability are more or less controlled by line voltage. Line voltage variation troubles can be lessened by using voltage-regulator tubes to supply the plate and capacitor charging voltages.
The added expense of voltage- regulator tubes can be eliminated without affecting timing stability if the line -voltage variation effects in the timing circuit can be made to cancel each other. The circuit shown here uses this principle see diagram. The timing circuit is controlled by S1. The length of the timing period is controlled by R2 and S2. Cl will then charge to a voltage determined by the setting of R2.
RI- 27, ohms, 1 watt R2- potentiometer, 15, ohms R This would normally cause the tube to conduct on half-cycles of the line voltage when line A is positive with respect to line B. However, the large voltage to which Cl is charged keeps the thyratron from firing. As Cl discharges through R3 or R4 or R5, depending on the range , the negative grid bias lowers to the point where the instantaneous grid cathode voltage allows the tube to fire. The tube current energizes the relay and turns off the apparatus being timed.