With its resistance built up to a value of ohms requires a

Potential of 0.3 volt (300 millivolts) to cause a full scale current of 1.0 milliampere to pass through the meter. FIG. 19 Front view arrangement of Supreme Model 339 radio set analyzer. FIG. 19 Front view arrangement of Supreme Model 339 radio set analyzer. The shunt resistor for the 5 milliampere range, being in parallel with the meter, will have the same 0.3 volt potential difference. Since 1.0 milliampere of the 5 milliampere range ' will pass through the meter, the shunt resistor will pass...

The Crystal Variously Called PiezoEIectric Pickup The

Action of this device, which on account of certain favorable qualities has found an increased use, depends upon the property of a Rochelle salt crystal in converting mechanical motion into electrical voltage. In practice this is accomplished by placing two small crystal slabs together which results in what is known as a bi-morph crystal element. This crystal element is then mounted between two small discs of sponge rubber in a bakelite housing, and a light aluminum rocker arm with rubber...

Grid provides a means for introducing the oscillator voltage into the detector circuit by electronic means

Receiving screen-grid tetrodes and screen-grid pentodes for radio-frequency voltage amplification are made in two types, known as sharp cut-off and variable-mu or super-control types, In. the sharp-cut off type the amplification factor is practically constant regardless of grid bias, while in the variable-mu type the amplification factor decreases as the negative bias is increased. The purpose of this design is to permit the tube to handle large signal voltages without distortion in circuits in...

Quarter more current into the battery than is taken out

If the lamp burn brighter than usual, turn the battery around. From 32 volt farm lighting plants only one 24 volt B battery can be charged from one lamp. 48 volt B batteries must be charged half (12 cells) at a time. Use either a 10 watt or a 20 watt 32 volt lamp. A 10 watt lamp charges at .1 ampere -20 watt lamp charges at .2 ampere. From 110 volt power lines, one, two or three 34 volt batteries can be charged from one lamp by connecting them in series...

The permanent magnet

A speaker of this type illustrated in figs. 4 and 5 consists principally of the following parts 1, field coil 2, voice coil 3, cone. FIG. 4 Cross-section view of a dynamic type loud speaker with a moving coil driving a cone type diaphragm. Details of the various units are here clearly represented. FIG. 4 Cross-section view of a dynamic type loud speaker with a moving coil driving a cone type diaphragm. Details of the various units are here clearly represented. The field coil...

Wireless Control System

By utilizing a device recently developed by the Philco Radio & Television Corp., it is possible to operate a radio receiver by means of remote control. The control box popularly known as the Mystery Control is portable, and the desired station may be dialed in a manner similar to that of a dial-type telephone, except that no connected wires are necessary. .With reference to fig. 11, showing the control box, the tube and coils form an oscillator which can be...

Through the choke coil and the internal plate circuit

Choke Coil Construction

Condenser C prevents this d.c. current flowing through coil L, when S is closed, thus preventing discharge of the B battery through coil L, and also making the reactances of the circuit LC to radio frequency current low. When S is closed a surge in current takes place via condenser C and coil L, which is absorbed from the internal plate circuit. Since the choke maintains the battery current steady, the variable current through coil L induces a voltage in coil L'. Assuming the induced voltage is...

C C Cc

EIG. 10 Illustrating condenser connection and mathematical relation between the total capacitance and the individual capacities when connected in parallel combination. FIG. 11 Arrangement of straight line capacity condensers for various capacities. The movable plates are made to intermesh (without touching) with those of the stationary plates, and the maximum capacity is obtained when the full areas of the two sets of plates are exposed to each other, and for various other positions some...

Info

PIG. 3 Schematic illustration of broadcasting principles. An oscillator or high frequency producing device (7) in the meantime produces radio waves (9) for broadcasting. A modulator (8) modulates or changes these radio waves to travel as sound waves. The varied currents (6) enter the modulator (8) and cause the radio waves (9) to float out as at (10) conforming to the electric sound waves. An amplifier (11) amplifies the modulated radiowaves as at (12) which enter the antenna (13) and emanates...

Receiver Construction

It cannot be denied that a commercial factory buijt receiver from the standpoint of appearance can be made much neater than most amateur built sets. This is due in most cases to the lack of necessary tools for handling the modern type of construction, found in ready built sets. It is undoubtedly true that with a few well-chosen tools, an otherwise time consuming piece of work may be turned out neat appearing, satisfactory and reliable from every point of view. Within certain limits it is...

R

These phototubes are made in two different types, namely, vacuum and gas-filled. The two types are identical as to structure but differ in that the high vacuum of the va uum type is replaced with an inert gas of a very low pressure in the gas-filled type. The chief advantage of the vacuum type of phototube is the light-current linear response characteristic however, the total current consists of only the primary electrons emitted from the light sensitive surface of the cathode. On account of...

Commonly used

However, on very long wavelengths it has been found advantageous to use step-up ratio transformers, by having a greater number of secondary than primary turns. -iliW'I'I'I'H b-battery FIG. 14 Three stage radio frequency amplifier circuit. -iliW'I'I'I'H b-battery FIG. 14 Three stage radio frequency amplifier circuit. In the transformer coupled circuit shown in fig. 14, the filaments are connected in parallel across the common A battery with a variable rheostat to adjust the filament current. A B...

How the Wave Length of an Aerial May Be IncreasedIt

Has been found convenient to include an inductance in the down lead wire to the receiver for the purpose of passing the received signal voltage to the set. Sometimes this added inductance coil is connected directly to the set and at other times it is coupled magnetically to the tuned circuit. When in the closed circuit type, a coil of inductance L micro-henries is connected in the down-lead of an aerial whose inductance is La micro-henries, the new wave-length is being given by . X 1,885V L La...

Ft these values may be substituted for Pi and P in equation

The logarithm of a number is the power to which 10 must be raised to equal the number in question. For example, log. 100 2 because 10 100. Similarly log. 867 2.9380 because 102'3380 867, etc. Example. What gain in decibels will be received if the voltage of an amplifier rises to 5 times the normal level at a certain frequency N 20 log.io 5 20X0.699 14 decibels Approx. Reference Level. It is important to note that the decibel is not a power unit such as the watt or kilowatt but is strictly...

Response in the Infra Red or Heat Wave Region The

Range of sensitivity of various photo-electric devices extends from 2,000 Angstrom in the ultra-violet region to approximately 20,000 Angstrom in the infra-red or heat wave region. In practice, one need not expect any useful response beyond 12,000 Angstroms in cesium-oxide phototubes. It seems doubtful at present if more than a mere trace of photo-electric effect will ever be experimentally realized for the infra-red region beyond, say, 30,000 Angstroms. Quite possibly dependence will have to...

At both audio and intermediate frequencies but filters must also

Be inserted to separate the frequencies so as to prevent feedback. A typical reflex circuit using one tube and a crystal detector is shown in fig. 28. Intermediate Frequency Amplifiers. The function of the intermediate frequency amplifier in a super-heterodyne receiver is to convert the r.f. signal to an intermediate frequency. To obtain this change in frequency, a frequency-converting device consisting of an oscillator and a frequency mixer is commonly employed. In a circuit of this type two...

Principles of Radio Telephony

Radio telephony may be defined as the transmission to a distance of speech, music and other sounds through space without wire, by means of electro-magnetic waves. In the standard system of radio telephony continuous waves are used of much higher frequency than those of audible sounds. The amplitude of those waves is modulated by the connection of a microphone in the transmitting circuit. Receiving apparatus are similar to those employed in radio telegraphy and are designed so that the head set...

Paper upon which theexactoutlineof the panel or chassis has been

The parts are generally moved around until a satisfactory arrangement has been obtained. The centers and sizeof the various holes are then laid out on the paper, after which the SCRATCH ON METAL TO FACILITATE BENDING One Side Only FIG. 2 After corners has been removed and the drilling and cutting completed, the projecting sides of the metal is bent down 90 to form the chassis as shown in fig. 4. paper is transferred to the panel and properly fastened by gummed paper or adhesive tape. Only...

Radio Batteries

There may be confusion in the minds of some as to batteries so a classification of types and functions will be helpful, particularly to the novice. Radio batteries may be classified according to the three elements of the vacuum tube which they serve, as A battery B battery C battery The three elements of the common vacuum tube, filament, plate and'grid are often designated by the letters A,.B and C. The order in which the letters are assigned corresponds to the historical development of the...

Vacuum Tubes

A vacuum radio tube in its simplest form is somewhat similar to an electric light bulb, but contains a number of metallic elements for various purposes for use in conjunction with radio transmission and reception. The parts of a typical vacuum tube is shown below. Fig. 1. Parts and assembly of a typical glass radio tube. The filament, grid screen and plate are sealed in the tube, from which the air has been removed. Courtesy R.C.A. Mfg. Co. ' Fig. 1. Parts and assembly of a...

Taper reamer in for brace

1 Taper reamer in. for brace. 1 Center punch. 1 Electric soldering iron 100 watts, small pointed tip . 1 Heavy knife 1 Circle cutter adjustable for brace. 1 Screw driver bit for brace. 1 Countersink for brace. 1 Carpenter's ratchet brace. . 1 1 Hand drill 2 speed . 1 Yardstick or other straight edge. x 1 Carpenter's plane 8 to 12 in. . 1 Combination square 12 in. . 1 Pr. wing dividers 8 in. . 1 Long shank screw driver with screw holding clip i i' n. , blade . 1 Screw driver 6 in. to 7 in. M in....

Public Address Systems

Ballroom Audio Sound System Wiring

By definition a public address system consists of a sound amplifier system supplying sound programs from radio, phonograph or microphones to one or more loud speakers. - VOLUME CONTROL REPRODUCER PICK-UP AMPLIFYING-RADIO RECEIVER AND CONTROL PANEL FIG. 1 Schematic view of a music reproducing and program distributing system. A public address system may be designed to amplify sound in one single place such as in an auditorium or in a number of rooms such as in hotels or hospitals. In order that...

The actuating wire has a tendency to expand when not in

Use, hence it is necessary to set the pointer back to zero before sending a current through it. 5. They are uneconomical, i.e. the current consumption is considerably in excess of that in other types. FIG. 16 Simplified diagram illustrating the construction of a hot wire instrument. AT, represents a silk thread connected to spring S, wound around pully P, and attached to a bead threaded on wire AB. Wire AB, made of platinum alloy, is connected in the circuit whose current is to be measured....

The decibel ranges provides measurements of power levels between to db

n r ----1 iWftiiiAM MndJ 779 nnnlvzpr. n r ----1 iWftiiiAM MndJ 779 nnnlvzpr. Weston Model 772 Analyzer. This analyzer is designed to make the necessary tests on present day equipment such as commercial radio receivers, transmitters, television receivers, FIG. 14 Wiring diagram of Weston Model 772 analyzer. FIG. 14 Wiring diagram of Weston Model 772 analyzer. public address systems, vacuum tube and cathode ray equipment, etc.

Physics of Sound

Piano Scale Note Chart Frequency

When air is set in vibration by any means, sound is produced provided that the frequency of vibration is such that it is audible. If a violin string in tension be plucked, as in fig. 1, it springs back into position, but due to its weight and speed, it goes beyond its normal position, oscillates back and forth through its normal position, and gradually comes to rest. These vibrations produce sound. As the string moves forward it pushes air before it and compresses it, also...

An oscillator frequency control circuit

How the Discriminator-Detector Circuit Works. The discriminator-detector network as the name implies, discriminates between applied intermediate frequencies which are too low and thpse which are too high, and produces a corresponding direct current or voltage whose polarity depends upon the direction of frequency departure from a prescribed intermediate frequency. This d.c. voltage is applied to a control element which in turn causes a shift in frequency of the local oscillator such as to bring...

Marine Radio Equipment

Radio Telegraph Transmitter

The Federal Communications Commission, by virtue of authority granted to it by the Communications Act of 1934, has promulgated various specifications and regulations applicable to ship-board radio installations. Most of these regulations are found in its General Orders and its rules and regulations. FIG. 1 Photographic view of S.S. Manhattan. View of radio room and equipment shown in fig. 2. FIG. 1 Photographic view of S.S. Manhattan. View of radio room and equipment shown in fig. 2. The...

Each radio beacon a definite signal

The common method of ascertaining the location of a ship equipped with radio compass is by means of cross bearings using two or more radio beams as shown in fig. 1 or by visual and radio bearings in combination. Of course the usual principles apply, as to employing stations which will give good intersections, and as to allowing for the compass aboard ship and shore radio beacons. compass aboard ship and shore radio beacons. distance run between the times of taking bearings if...

Phototube Relays

Since as already described the current change accomplished in photoelectric cells is very small, it is necessary to employ an amplifier in order to receive a current of sufficient strength to operate a relay. When selecting a relay for operation in a photoelectric circuit, it is of course necessary to be informed about the characteristics of the circuit, speed of operation, etc. It is also important that the relay employed is able to carry the load to be operated across its contacts without...

Phonograph Pickups

By definition a phonograph pick-up is a device which converts the vibrations of a phonograph needle in traversing a phonograph record into audio frequency currents for reproduction through a radio receiver. See fig. 1. motor leads PIG. 1 Modern phonograph pick-up unit. motor leads PIG. 1 Modern phonograph pick-up unit. Phonograph pick-up operating on various well known principles have been developed, such as the condenser type, carbon resistance, magnetic or crystal type. The pick-ups at...

Procedure of making this test

Ened to cardboards and insulated from contact with car body. ened to cardboards and insulated from contact with car body. FIG. 2 Illustrating location of roof type antenna. FIG. 2 Illustrating location of roof type antenna. x If it be found that the top support screen is grounded or if no screen be present, it will be necessary to remove the entire head-lining as shown in fig. 2. In the former case the screen may be insulated by removal of a strip several inches from all edges, as well as from...

Radio Telephone

Diagram Komunikasi Radio

FIG. 1 Diagrammatic representation illustrating similarity between wire and radio telephone. It is thus possible for the personnel of the above to communicate with their offices or homes when within range of a coastal harbor radio telephone station. At present radio telephone service is available to boats in the areas served by the shore stations at Boston, New York, Miami, Seattle, San Francisco, Los Angeles and Norfolk. In this connection it may be mentioned, that the regulation of the...

Thereby forming what is known as a ring type shunt the

Construction View Voltmeter Image

Total ring resistance value being 375 ohms. The resistance values of the 75 ohm shunt resistors are determined by multiplying the total ring resistance by the full scale current of the meter, dividing the result by each range value, in turn, from the common terminal, and subtracting the sum of the preceding values from each newly-determined value. When the ring value of 375 ohms is multiplied by the full scale sensitivity value of 0.001 ampere, 0.375 is the result, into which each range value...

Sensitivity

The three groups are inter-dependent with selectivity th lt most important factor. FIGS. 1 and 2 Block diagrams showing essential units of a regenerative and a tuned radio frequency regenerative circuit respectively. FIGS. 3 and 4 Block diagrams showing essential units of a super-regenerative and a super-infra regenerative circuit respectively. By definition,' selectivity of a receiver is its ability to discriminate between signals of various frequencies. The sensitivity of a receiver is the...

Questions and Answers

It is now generally recognized that successful radio receiver trouble-shooting or radio servicing requires an intimate knowledge of thousands of component parts constituting the receiver. Years ago, when the best receiver consisted of a condenser, a coil and the catwhisker thrown together in haphazard manner, anybody in possession of a buzzer, a pliers and a screw-driver, could find and eliminate the trouble in short order. However, since then, radio receivers have gone through an epoch of...

Automatic Radio Alarm

Ar8600 Schaltplan

An automatic alarm is a device used to enable a ship in distress to summon aid at any time by radio from a nearby vessel, and especially during those periods when the radio operator on the nearby vessel might not be on watch. Special regulations governing this distress signal and the number of operators which their installation shall release are now in force. 0 5 10 15 20 25 30 35 40 45 50 55 . 60 SECONDS 1 i m 1 I i i i i I 1 i i i I 11 ii I i m i ii i i 1 m i 1 i 1 ii 1 i ii 1 i t i i I i i i...

Aircraft Radio

Antique Aircraft Loop Antenna

It is undoubtedly true that without the aid of radio, aerial navigation would not have advanced to the stage where giant airliners arrive and depart keeping time schedules unheard of only a few years ago. As a matter of fact the airplane is rapidly closing in on such proven means of transport as trains, ships and buses in regards to exact time schedules in all sorts of weather. It is a recognized fact that the actual value of aircraft radio installations depends entirely upon radio facilities...

ABCw

Where L Inductance in micro-henries A Inside diameter of coil in inches C Radial depth of coil in inches which value may be omitted for single layer coils This formula will be of assistance and is preferred to the cut and try methods which are often found to be of little help when exact values of inductance are required. Sometimes it may be most convenient to use an existing coil, form in which case the diameter is given, the only trouble being then, to determine the number of turns of a...

Galvanometer is used r the radius of the coil in centimeter

6, the angle of the needle deflection in degrees and I, the current in c.g.s. units. FIG. 1 The tangent galvanometer consists essentially of a short magnetic needle suspended at the center of a coil of large diameter and small cross-section. In practice the diameter of the coil is approximately 17 times the length of the needle. If the instrument be so placed, that when there is no current in the coil, the suspended magnet lies in the plane of the coil, that is, if the plane of the coil be set...

Tube Heterodyne Receiver Circuit

Dio General Electric 260 Schematic

' x p' -1 nifr i rectifierj ' x p' -1 nifr i rectifierj lt k 84 Fig. 8. Circuit diagram of a 7-tube automobile radio receiver, Philco Lincoln-Zephyr L-1424. This receiver is equipped ' with an electro-dynamic speaker, which is mounted on the rear of the instrument board extension. The volume control is automatic, a specially designed input circuit to match thetire compartment door antenna, and an elaborate filter network to reduce ignition noise disturbance is included. The receiver is designed...

The instrument is illustrated in fig and its connection diagram in fig

Weston Selective Analyzer

It has a 20,000 ohms per volt sensitivity on five d.c. voltage ranges. A.c. readings are made on single arc scale. The ranges for dx. current measurements are 0- 0.1 10 50 -250 m.a. la lOa. Ax. or dx. voltage measurements have the following ranges 0-2.5 10 50 250 1,000 v. Five decibel ranges provide power level measurement from 14 to 54 db. Resistances are measured on the following scales 0-3,000 -30,000 3 Meg. 30 Megohms. The instrument is equipped with pin jacks for mounting model 666 socket...

Dynamic speaker previously described

FIG. 6 When the dynamic speakers as in some commercial sets are connected by means of plug and cable to the chassis, the connections may be as shown in fig. 6 or 7 generally however, there is no set rule for these connections. The output transformer may be mounted on the receiver chassis' or on the speaker frame. Again, the output tubes may be connected in parallel or in push-pull. Therefore, the connections shown are'typical only and may not be considered as standard, but in each case the...

Phototube Amplifiers

Since the current generated in most photocells is very low and is usually measured in microamperes, it is evident that for practical operation a way must be found to increase this feeble current, for practical relay operation. Therefore in order to increase the power output of the photocell a method of amplification very similar to that associated with radio circuits is employed. The amplifier tubes may be of the high vacuum or of the gaseous type. .When the...

Radio Circuit Diagrams

Rca Victor 18t Wiring Diagram

Schematic wiring diagram of a 4-tube Handy-phone for inter-office communication. Model FM-41 General Electric. The handy phone is an efficient loudspeaker phone system for use in offices, homes, hospitals or other places where voice,communication between a central station and one of more remote stations is desirable. The system comprises one Model FM-41 master station and from one,to four Moddl FS-5 remote speaker phone stations. The master station employs four General Electric tubes in...

Commercial Type Analyzers

Weston Selective 665

The external view of this instalment is shown in fig. 4. and its internal connection diagram in fig. 5. The instrument is principally a volt-ohm-milliammeter for All voltage ranges are available at the pm jacks, and by means of socket selector units may be had through the plug. They are 0-1 2.5 5 10 25 100 250 500 1,000 volts, eithef a.c. or d.c. The individual ranges are selected by means of the large selector switch. A reading cannot be had till either the...

Using Ohms law EIR X

Voltage Selector Switch

Or 1,000 250 0.001X fromwhichX -QQQ 750,000 ohms. The resistor to be inserted should have a value of 750,000 ohms and each reading taken after insertion of this new resistance should be multiplied by 4 to obtain the true voltage. A Combination Volt-Ammeter. Since the construction of a voltmeter and ammeter is the same, the difference being that in an ammeter resistors are placed parallel to the moving coil, while in the voltmeter resistors are placed in series with the moving coil, it is...

Principle of Operation

Radio Antena Switch Diagram

The radio compass is an imti ument for observing by means of radio, the direction of a station emitting radio signals briefly, in aerial and marine navigation, it is an instrument for taking radio bearings. Operating Principles. Since the radio compass is built around the loop antenna it is necessary to understand its principles of operation before undertaking a study of the other units. The radio compass utilizes the directional receiving properties of the coil, which consists essentially of...

The Cathode Ray Oscillograph

Cathode Ray Oscilloscope Circuit Diagram

The cathode ray oscillograph is at present one of the most useful of radio testing devices. Although as yet relatively expensive, its applications are so numerous that it will readily replace a number of measuring instruments of more or less satisfactory characteristics. A few of the more important applications of the instrument are the study of wave shapes and transients, measurements of modulation and peak voltages, adjustment of radio receivers, comparison of frequencies, the indication of...