US2108642A - Magnetic device - Google Patents
Magnetic device Download PDFInfo
- Publication number
- US2108642A US2108642A US96927A US9692736A US2108642A US 2108642 A US2108642 A US 2108642A US 96927 A US96927 A US 96927A US 9692736 A US9692736 A US 9692736A US 2108642 A US2108642 A US 2108642A
- Authority
- US
- United States
- Prior art keywords
- windings
- output
- current
- circuit
- positive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000005291 magnetic effect Effects 0.000 title description 33
- 238000004804 winding Methods 0.000 description 97
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 3
- 239000005751 Copper oxide Substances 0.000 description 3
- 229910000431 copper oxide Inorganic materials 0.000 description 3
- 230000005415 magnetization Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F9/00—Magnetic amplifiers
- H03F9/02—Magnetic amplifiers current-controlled, i.e. the load current flowing in both directions through a main coil
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F9/00—Magnetic amplifiers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/20—Repeater circuits; Relay circuits
Definitions
- This invention relates to magnetic devices and more particularly to magnetic amplifiers for amplifying electrical impulses.
- the usual magnetic amplifier circuits are not responsive to both positive and negative current impulses, or elsethey cannot differentiate between these two kinds of impulses. is desired or necessary to repeat either two or three-element signals comprising both positive and negative current impulses, or positive, negative and zero current impulss" it has been necessary in the past to either provide two magnetic amplifiers and modulating systems therefor, one to repeat the positive current'impulses and "the other to ,repeat the negative current impulses; or to bias an amplifier so that positive impulses will increase the output while negative impulses will decrease the output of the amplifier.
- the double amplifier is both bulky and expensive while the use of a bias necessitates a balancing circuit to balance out the normal steady output of the amplifier in case it is desired to transmit both positive and negative signal impulses from the amplifier.
- These balancing arrangements tend to make the amplifier unstable and introduce distortion into the signals.
- two sets of output windings are provided on a single magnetic modulating system of either a single or pair of modulating cores.
- Half-wave rectifiers or demodulators are connected to these output windings so that one of them will pass peaks due to In case it positive impulses applied to the input circuit and the other so that it will pass the peaks due to negative impulses applied to the input circuit.
- windings and demodulators are then con-' nected to an output circuit in such a way as to transmit or apply the respective positive and negative impulses to the output circuit.
- Fig. 1 illustrates a preferred embodiment of this invention employing a single modulating system comprising two magnetic cores for repeating and amplifying telegraph signal impulses of both positive and negative polarity;
- Figs. 2 and 2A show a simplified magnetic amplifier for repeating both positive and negative signal impulses employing a single magnetic.
- Network I8 is provided to reduce the impedance of the power circuit and to control the current flowing therethrough.
- the power windings l2 and I3 are so proportioned with respect to cores l0 and l I and source l'l that the cores are saturated during aportion of each half cycle of the alternating current from source ll.
- Cores l0 and l l are provided with input windings I5 and I6. These windings are so connected that when there is no input signal potential applied to them or when there is no input current flowing through them the potential induced'in winding l5 by core I0 and winding I2 is opposed by an equal and opposite potential induced in winding l6 by core H and winding l3.
- Frequency discriminating network i9 is connected in the input circuit to prevent currents due to this voltage from disturbing the input circuit and line 23 and also to prevent changes or the impedance of the line 23 to this harmonic voltage or current from affecting or disturbing the operation of the amplifier. Consequently, frequency discriminating network I! comprising elements 26, 2i and 22 may include low-pass filters, band pass filters, band suppression filters, or high suppression as well as equalizing elements and networks.
- telegraph signal impulses are distorted in form by the transmission line over which they are transmitted.
- the signal impulses are further distorted by the input circuit of the magnetic amplifier.
- In order to secure the required sensitivity for the amplifier it is necessary to provide a large number of turns in the input windings. This increases the inductance of the winding and also the time constant of the input circuit so the amplifier does not respond as much to short impulses as it does to long impulses.
- may include equalizing elements, sections, or networks for improving the shape of the telegraph signal impulses as well as for increasing or equalizing the response of the amplifier to short signal impulses.
- the cores I and l l are provided with two sets of output windings. Windings 25 and 25 of cores l6 and H provide one set of output windings and windings 26 and 21 of cores l0 and i I provide the second set of output windings. Each set of output windings is connected through a half wave copper oxide rectifier or other suitable demodulating devices 28 and 29, respectively, to windings 39 and 40 of relay 36, a second frequency discriminating network including equalizin'g network 32 comprising elements 33, 34 and 35 is connected in this circuit to further improve the wave form of the signal impulses transmitted to relay 36. As shown in Fig. 1,relay 3B is provided with a vibrating circuit and winding comprising a. condenser 4
- a harmonic potential which in the preferred embodiment is 1 preponderantlythe second harmonic of source l1, that is, a potential of twice the frequency of source I1, is induced in both output'circuits and aioaeea causes a voltage of the corresponding frequency to be applied to the respective demodulators 28 and 29 and their associated circuit.
- Fig. 3A illustrates the wave shape of the potential induced in the output windingson cores ill and it during the time a positive impulse or positive current therefrom is flowing through the input windings i5 and it.
- line 56 represents the zero potential line.
- the potential of positive half cycles is much higher than the potential of the negative half cycles.
- One rectifier or demodulator 28 is connected to the output circuit comprising windings 24, 25 in such a manner that it will pass these high positive peaks while the rectifier or demodulator 29f'is connected oppositely to the output circuit comprising windings 26 and 21, that is, it is connected so that it passes the low potential negative peaks, but does not pass the high potential positive peaks.
- These rectifier elements have non-linear characteristics similar to copper oxide rectifiers in which the impedance in the forward or conducting direction falls or decreases rapidly as the potential applied to them increases.
- the demodulated or output currentfiowing through devices 28 and 29 also flows through the output windings 24, 25, 26, and 21.
- the demodulated current flowing through windings 24 and is in a direction to aid the magnetic effect of the positive input current while the demodulated output current flowing through windings 26 and 21 is in the direction to oppose the magnetic eifect of the positive current flowing in the input windings.
- the current flowing through windings 24 and 25 and device 28 greatly exceeds the current flowing through the windings 26 and 21 and device 29, the net effect is that the demodulated output current flowing through the output windings tends to aid the input positive current flowing in the input circuit and thus causes a regenerative feedback action which increases the output of the amplifier.
- windings on cores l and H have understood that various windings such as been described as individual windings it is to be l and I6, 24 and 25, 26 and 21, may be combined into a single winding providing they interlink each of the cores so that the respective circuits will have voltages induced in them in the same manner as the cores induce voltages in the circuits described in Fig. 1.
- the output circuit shown in Fig. 2 to be described herematter may be provided for retransmitting the signal impulses to another telegraph line, load or other receiving apparatus.
- the output circuit may be connected to the input circuit of a similar amplifier thus forming a multi-stage magnetic amplifier.
- the amplifier shown in Fig. 1 is also applicable to amplifying three-element signals, that'is, signals of positive, negative and zero polarity.
- input windings l5 and 16 are each provided with 2100 turns; power windings i2 and i3 with 450 turns each; output windings 24, 25, 26, and 21 with 400 turns each; network l8, a resistance of 300 ohms and a capacity of 0.016 microfarad; condensers 30 and 3
- each demodulator 28 and 29 comprises 8 copper oxide rectifier discs inch in diameterconnected in series; source I], a voltage of 34 volts at 2160 cycles per second; elements 33, a resistance of 3000 ohms and a capacity of 8 microfarads; elements 34 and 35 were not required for this particular amplifier and were not provided; and relay 36 was a polarized telegraph relay having windings 39 and 40 of 3800 turns and 3'70 ohms resistance each, and windings 31 and 38 of 800 turns each; the resistances in the vibrator circuit were 10,000 ohms each and the condenser had a capacity of 0.5 microfarad; and 130' volt positive and 130 volt negative .batteries were connected to the con- .tacts of relay 36.
- the embodiment of this invention shown in Fig. 2 employs only a single saturable core 50 in combination with other circuit elements to amplify both positive and negative electrical impulses or current.
- Core 50 is provided with a powersupply winding '5l which is connected through networks I and to a source of alternating current ll.
- Networks I8 are provided to reduce the impedance of the power supply source I1 flowing through winding 50 does not normally saturate core 50 unless current is also flowing through the input winding 52.
- Core 50 is provided with an input winding 52 which is connected to line 23 through a frequency discriminating network including ,equalizer 2l and a low-pass filter network l9. It is to be understood that this frequency discriminating network may assume any suitable form and include any of the elements described with reference to the frequency discriminating network of Fig. 1.
- the input circuit may be connected to bridge circuits or to any other indicating instrument which furnishes only a small amount of power which it is desired to amplify.
- the frequency discriminating network 2lshown in Fig. 2 tends to improve the wave shape of the received signals, to counteract the efiect of the high inductance of the input winding, and correct for the distortion due to the line and compositing networks.
- the low-pass filter I9 prevents currentinduced'in winding 52 by the alternating current supply I! from flowing in line 23, and prevents changes in impedance of line 23 to this current from affecting the operation of' the ampliflerj Core 50 is provided with two. output windings 53 and 54.
- rectifiers are connected through resistances 60 and SI the center'tap of which is connected to the center point of condensers 30 and 3
- the rectifiers are alsoconnected to load or line circuit 55.
- Load 55 may be any suitable receiving device, load, input circuit of another amplifie telegraph line, meter, etc.
- the low pass filter l9 prevents this potential from performing any useful or detrimental function.
- an input current flows through the input winding 52 it will tend to alter-the magnetization of core 50 so that it will tend to become saturated during a portion of one-half cycle of the alternating current from source II, but will not be saturated duringthe other half cycle.
- the voltages induced in windings 53 and 54 will again become distorted similar to that shown -in Figs. 3A or 3B. In this case again the voltages will be of the same frequency as source l9 and nota harmonic thereof as in the case of Fig. 1.
- the demodulated current flowing in the output circuit also flows in the output windings 53 and 54 and, as described with reference to Fig. 1, tends to increase the gain and output of the amplifier arrangement shown in Fig. 2 when both.
- the amplifier is capable of receiving both positive, negative and zero sig nal impulses and transmitting the corresponding impulses in amplified form to line or load 55.
- the load'circuit in Fig. 2 might be applied equally well to the amplifier shown in Fig. 1. All that is necessary is that the three wires to the right of the dot-dash line of Fig. 2 be connected to the three wires from the equalizing network 32 of Fig. 1. In this case the amplifier shown in Fig. 1 will amplify and transmit signal impulses of a positive negative and zero polarity.
- Fig. 2A shows an alternative output circuit which may be connected to the amplifiers shown in either Figs. 1 or 2.
- the relay When this circuit is connected to the circuit shown in Fig. 2 the relay will be energized so as to close its armature to the positive contact in response to a positive signal impulse received over line 23.
- the positive impulse received over line 23 causes the current flowing through the element 28to greatly exceed I the current flowing through element 29 so that the current flowing through" winding 39 of relay 36 of Fig. 2A will greatly exceed the current flowing through winding 40 thereof and cause the relay armature to move to the positive contacts.
- a negative impulse is received from line 23 it causes a considerably greater current to flow through element 29 than flows through element 28. Consequently a greater current flows through winding 40 than flows through winding,39. This will cause the relay armature to move it to the negative contact. Consequently the relay operates in response to the signal impulses received over line 23.
- equalizing networks may be so arranged that av considerable greater gain of over 20 decibels may be obtained for certain frequencies.
- a magnetic amplifying device comprising a single modulating system, a power supply circuit for said system, an input circuit for said system, two sets of output circuits for said system, a unilateral non-linear conducting device connected to each of said output circuits, in opp'osite directions, so that one of said conducting devices passes'current' during one-half cycle of one polarity of the output current and the other of said devices passes current during the other half cycle of the opposite polarity and an energy inopposite directions.
- a magnetic amplifying device comprising a single magnetic modulating system comprising a single core of saturable material, a power supply winding on said core, an input winding on said core, two sets of output windings wound on said core, a unilateral nonlinear conducting device connected to each of said output windings in opposite directions and a load circuit including said output windings and unilateral conducting devices connected in opposite directions.
- a magnetic amplifying device employing a single magnetic modulating system comprising a pair of saturable magnetic cores, power windings wound on said cores, a source of alternating current power connected to said windings, said alternating current being of suflicient magnitude to saturate both of said cores during a portion of each half cycle of said alternating current, two sets of output circuits including output windings wound on said cores, an input circuit including input windings wound on said cores, a nonlinear unilateral conducting device connected to each set of said output windings in opposite directions and an output circuit to which said sets of and the other of said output circuits responds more to input signal impulses of negative polarity than said first-mentioned output circuit, and a load circuit connected to said output circuits whereby said load circuit receives positive signal impulses in response to received positive signal impulses and receives negative signal impulses in response to negative signal impulses received by said magnetic amplifying device.
- a magnetic amplifying device for amplifying signal impulses of positive, negative and zero polarity employing a single modulating system comprising a pair of saturable magnetic cores, power windings interlinking said cores, a source of alternating current power of sufllcient magnitude to saturate said cores during a portion of each half cycle of the current from said power source connected to said power windings, an input circuit interlinking said cores, frequency discriminating networks connected to said input circuit, two output circuits interlinking said cores, a non-linear unilateral conducting device connected to each of said sets of output circuits, said unilateral conducting devices being connected to pass opposite half cycles of the power induced in said output windings, and an energy utilizing circuit so connected to one of said output circuits as to receive positive signal impulses therefrom in response to a positive signal impulse applied to said input circuit and so connected to the other of said output circuits as to receive negative signal impulses therefrom in response to received negative signal impulses whereby signal impulses of positive, negative, and zero polar
- An amplifying system comprising in combination a single magnetic modulating system, power supply windings interlinking said system, an input circuit interlinking said system, two output circuits interlinking said system, a unilateral conducting device connected to each of said output circuits to pass opposite half cycles of current induced in said output circuits and a two position responsive device connected to said output circuits whereby said device will assume one position in response to signal impulses of one polarity applied to said input circuit and will assume the other of said positions in response to signal impulses of the opposite polarity applied to said input circuit.
- An amplifying system comprising in combination a single magnetic modulating system
- said output circuits in a manner to pass opposite half cycles of current induced in said output circuits and to cause said opposite half cycles to flow in said output circuit interlinkages to'increase the output of said device, and an energy utilizing circuit connected to said output circuits oppositely whereby one of said output circuits transmits positive impulses to said energy utilizing circuit and the other of said output circuits transmits negative impulses to said energy utilizing circuit.
- An amplifying system comprising in combination a single magnetic modulating system, power supply windings inter-linking said modulating system for normally. energizing all the elements of said modulating system to substantially the same magnitude during each half cycle of the alternating power supply, an input circuit interlinking said system, two output circuits inrent flowing in said input circuit and an amplified negative current flows in said output circuit in response to a negative current flowing in said input circuit.
- An amplifying system comprising'in combination a single magnetic modulating system, power windings interlinkingsaid system, an input circuit interlinking said system, an output circuit interlinking said system, a load circuit, an operative connection between said output circuit and said load circuit including two non-linear unilateral conduction devices connected oppositely to said output circuit whereby an amplified positive current flows in said output circuit in response to a positive current flowing in said input circuit and an amplified negative current flows in said output circuit in response to a negative current flowing in said input circuit.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Amplifiers (AREA)
- Amplitude Modulation (AREA)
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US96927A US2108642A (en) | 1936-08-20 | 1936-08-20 | Magnetic device |
GB20432/37A GB481255A (en) | 1936-08-20 | 1937-07-23 | Improvements in or relating to magnetic amplifiers |
BE422786D BE422786A (xx) | 1936-08-20 | 1937-07-23 | |
NL83541A NL49656C (xx) | 1936-08-20 | 1937-07-30 | |
FR825770D FR825770A (fr) | 1936-08-20 | 1937-08-19 | Amplificateurs magnétiques |
CH211211D CH211211A (de) | 1936-08-20 | 1937-08-20 | Magnetischer Verstärker. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US96927A US2108642A (en) | 1936-08-20 | 1936-08-20 | Magnetic device |
Publications (1)
Publication Number | Publication Date |
---|---|
US2108642A true US2108642A (en) | 1938-02-15 |
Family
ID=22259767
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US96927A Expired - Lifetime US2108642A (en) | 1936-08-20 | 1936-08-20 | Magnetic device |
Country Status (6)
Country | Link |
---|---|
US (1) | US2108642A (xx) |
BE (1) | BE422786A (xx) |
CH (1) | CH211211A (xx) |
FR (1) | FR825770A (xx) |
GB (1) | GB481255A (xx) |
NL (1) | NL49656C (xx) |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2556083A (en) * | 1943-08-14 | 1951-06-05 | Hartford Nat Bank & Trust Co | Magnetic amplifier |
US2657281A (en) * | 1950-02-15 | 1953-10-27 | Ward Leonard Electric Co | Electromagnetic audio amplifier |
US2697813A (en) * | 1951-04-12 | 1954-12-21 | Warren Webster & Co | Magnetic amplifier system |
US2710313A (en) * | 1948-10-12 | 1955-06-07 | Vickers Inc | Electromagnetic audio amplifiers |
US2719885A (en) * | 1951-07-20 | 1955-10-04 | Jr Robert A Ramey | Magnetic amplifier with high gain and rapid response |
US2783315A (en) * | 1951-07-20 | 1957-02-26 | Jr Robert A Ramey | Magnetic amplifier control circuit |
US2798168A (en) * | 1954-07-27 | 1957-07-02 | Sperry Rand Corp | Magnetic amplifier and flip-flop circuit embodying the same |
US2812389A (en) * | 1952-04-19 | 1957-11-05 | Cgs Lab Inc | Magnetic amplifier |
US2827603A (en) * | 1954-05-24 | 1958-03-18 | Librascope Inc | Electric motor positioning system using a magnetic amplifier |
US2831929A (en) * | 1946-06-27 | 1958-04-22 | Rossi Bruno | Magnetic amplifier |
US2882352A (en) * | 1954-11-19 | 1959-04-14 | Honeywell Regulator Co | D. c. amplifier system |
US2926300A (en) * | 1954-06-16 | 1960-02-23 | George A Rubissow | Push-pull magnetic amplifier and circuits therefor |
US2947946A (en) * | 1953-02-17 | 1960-08-02 | Int Standard Electric Corp | Magnetic switch-amplifiers |
US3064181A (en) * | 1956-09-04 | 1962-11-13 | Bell Telephone Labor Inc | Magnetic amplifier |
US4278938A (en) * | 1979-07-27 | 1981-07-14 | Bell Telephone Laboratories, Incorporated | Electromagnetic arrangement for measuring electrical current |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE899369C (de) * | 1938-06-01 | 1953-12-10 | Aeg | Verstaerker fuer kleine Gleichstroeme, insbesondere fuer Messzwecke |
DE758289C (de) * | 1938-08-19 | 1953-03-02 | Siemens App | Richtungsempfindlicher Magnetverstaerker |
US2820109A (en) * | 1952-03-22 | 1958-01-14 | Cgs Lab Inc | Magnetic amplifier |
-
1936
- 1936-08-20 US US96927A patent/US2108642A/en not_active Expired - Lifetime
-
1937
- 1937-07-23 BE BE422786D patent/BE422786A/xx unknown
- 1937-07-23 GB GB20432/37A patent/GB481255A/en not_active Expired
- 1937-07-30 NL NL83541A patent/NL49656C/xx active
- 1937-08-19 FR FR825770D patent/FR825770A/fr not_active Expired
- 1937-08-20 CH CH211211D patent/CH211211A/de unknown
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2556083A (en) * | 1943-08-14 | 1951-06-05 | Hartford Nat Bank & Trust Co | Magnetic amplifier |
US2831929A (en) * | 1946-06-27 | 1958-04-22 | Rossi Bruno | Magnetic amplifier |
US2710313A (en) * | 1948-10-12 | 1955-06-07 | Vickers Inc | Electromagnetic audio amplifiers |
US2657281A (en) * | 1950-02-15 | 1953-10-27 | Ward Leonard Electric Co | Electromagnetic audio amplifier |
US2697813A (en) * | 1951-04-12 | 1954-12-21 | Warren Webster & Co | Magnetic amplifier system |
US2719885A (en) * | 1951-07-20 | 1955-10-04 | Jr Robert A Ramey | Magnetic amplifier with high gain and rapid response |
US2783315A (en) * | 1951-07-20 | 1957-02-26 | Jr Robert A Ramey | Magnetic amplifier control circuit |
US2812389A (en) * | 1952-04-19 | 1957-11-05 | Cgs Lab Inc | Magnetic amplifier |
US2947946A (en) * | 1953-02-17 | 1960-08-02 | Int Standard Electric Corp | Magnetic switch-amplifiers |
US2827603A (en) * | 1954-05-24 | 1958-03-18 | Librascope Inc | Electric motor positioning system using a magnetic amplifier |
US2926300A (en) * | 1954-06-16 | 1960-02-23 | George A Rubissow | Push-pull magnetic amplifier and circuits therefor |
US2798168A (en) * | 1954-07-27 | 1957-07-02 | Sperry Rand Corp | Magnetic amplifier and flip-flop circuit embodying the same |
US2882352A (en) * | 1954-11-19 | 1959-04-14 | Honeywell Regulator Co | D. c. amplifier system |
US3064181A (en) * | 1956-09-04 | 1962-11-13 | Bell Telephone Labor Inc | Magnetic amplifier |
US4278938A (en) * | 1979-07-27 | 1981-07-14 | Bell Telephone Laboratories, Incorporated | Electromagnetic arrangement for measuring electrical current |
Also Published As
Publication number | Publication date |
---|---|
CH211211A (de) | 1940-08-31 |
NL49656C (xx) | 1940-12-16 |
BE422786A (xx) | 1937-08-31 |
GB481255A (en) | 1938-03-08 |
FR825770A (fr) | 1938-03-14 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2108642A (en) | Magnetic device | |
US2164383A (en) | Magnetic device | |
US2211750A (en) | Wireless telegraph system | |
GB625532A (en) | Improvements in electrical wave translating systems | |
US2998487A (en) | Transistor switching arrangements | |
US2341526A (en) | Amplifying and detecting system | |
US1477017A (en) | Current-controlling and static-reducing system | |
US2899548A (en) | channel | |
US2393400A (en) | Frequency yariation response circuit | |
US2019481A (en) | High frequency modulation system | |
US2545250A (en) | Frequency changing circuit | |
US2572074A (en) | Voice-frequency signaling system | |
US2199190A (en) | Noise suppression | |
US2184978A (en) | Carrier current telegraphy | |
US1959275A (en) | Method of and apparatus for controlling alternating currents | |
US2343753A (en) | Receiving circuit for telegraph signaling systems | |
US3265980A (en) | Full wave synchronous demodulator | |
US2715203A (en) | Electric motor control circuit using saturable reactors | |
US2248857A (en) | Automatic bias corrector | |
US2085927A (en) | Receiving apparatus for communication systems | |
US2229806A (en) | Switching device for echo blocking and feed-back blocking | |
US3596194A (en) | Electronic signal converter | |
US3479617A (en) | Hybrid circuit arrangement | |
US2043355A (en) | Carrier telegraph receiver | |
US2775649A (en) | Telephone subscriber sets |