GB509613A - Improvements in electric signal amplifiers incorporating voice-operated devices - Google Patents

Improvements in electric signal amplifiers incorporating voice-operated devices

Info

Publication number
GB509613A
GB509613A GB185238A GB185238A GB509613A GB 509613 A GB509613 A GB 509613A GB 185238 A GB185238 A GB 185238A GB 185238 A GB185238 A GB 185238A GB 509613 A GB509613 A GB 509613A
Authority
GB
Grant status
Application
Patent type
Prior art keywords
amplifier
speech
output
transformer
loud
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
Application number
GB185238A
Original Assignee
Leonard Ernest Ryall
Priority date (The priority date 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 date listed.)
Filing date
Publication date

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B3/00Line transmission systems
    • H04B3/02Details
    • H04B3/20Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other

Abstract

509,613. Two-way transmission. RYALL, L. E. Jan. 20, 1938, No. 1852. [Class 40 (iv)] In a loud-speaking system with voiceoperated switching devices, break-in is permitted, but acoustic reaction prevented, by arranging that the output of the loud-speaker is deficient in low frequencies and that the switching devices which condition the transmitting path are responsive to the preponderance of low-frequencies present in actual speech. The deficiency in low-frequencies of the loud-speaker output may be due to such deficiency in the distant microphone which is natural in the carbon type and may be deliberately effected in, say, a moving coil type in order also to reduce the effects of room reverberation. The transmitting and receiving amplifier may as regards speech as distinguished from control paths favour the high frequencies and the loud-speaker may itself be deficient in low frequencies. The control path of the transmitting amplifier favours low frequencies. In the arrangement shown, which is similar in some respects to arrangements described in Specifications 415,767, 416,372 and 430,567, a bridge comprising resistances 13, 14 and valves 3, 8 of the transmitting and receiving amplifiers respectively, is adjusted so that normally the points 15, 16 are at the same potential and a small current flowing from 16 to 17 controls rectifiers 18-20 associated with a winding of the input transformer 7 of the receiving amplifier 3 and rectifier 24, 25 associated with a winding of the speech output transformer 5 of the transmitting amplifier 8, whereby the output transformer is effectively shunted and the input transformer is operative. Speech currents from the microphone are rectified in the secondary circuit of a control output transformer 4 and reduce the negative bias of the receiving valve 8 whereby the balance of the bridge is upset and current flows from 17 to 16 to cause the conditions of the input and output transformers to be reversed if the lowfrequency output of valve 3 predominates, transformer 4 feeding the rectifier being tuned to a low frequency. Speech incoming from the line is rectified at a secondary winding of transformer 9, another winding of which supplies the loud-speaker 10 and the rectifier current increases the effect of the normal current between 16 and 17. The rectifier load on the amplifying valves, in series with speech path load in case of amplifier 3 but in parallel in case of amplifier 8, gives rise to harmonic distortion in the speech paths and to minimize this effect, amplifier 3 is arranged for series negative feed-back over resistance 26 and amplifier 8 is arranged for parallel feed-back by means of a further secondary winding 23 of output transformer 9, whereby the outputs of the amplifiers are substantially independent of the load impedance of the associated rectified control-current supply circuits.
GB185238A 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices Expired GB509613A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB185238A GB509613A (en) 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB185238A GB509613A (en) 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices
GB1744139A GB509693A (en) 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices

Publications (1)

Publication Number Publication Date
GB509613A true true GB509613A (en) 1939-07-19

Family

ID=9729126

Family Applications (2)

Application Number Title Priority Date Filing Date
GB185238A Expired GB509613A (en) 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices
GB1744139A Expired GB509693A (en) 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices

Family Applications After (1)

Application Number Title Priority Date Filing Date
GB1744139A Expired GB509693A (en) 1938-01-20 1938-01-20 Improvements in electric signal amplifiers incorporating voice-operated devices

Country Status (1)

Country Link
GB (2) GB509613A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3026374A (en) * 1958-06-26 1962-03-20 John K Hilliard Voice-control telephone conference system
US3050584A (en) * 1958-12-24 1962-08-21 American Telephone & Telegraph Conference telephone apparatus
US3136864A (en) * 1959-10-05 1964-06-09 Automatic Elect Lab Loudspeaking telephone with electronic voice switching

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3026374A (en) * 1958-06-26 1962-03-20 John K Hilliard Voice-control telephone conference system
US3050584A (en) * 1958-12-24 1962-08-21 American Telephone & Telegraph Conference telephone apparatus
US3136864A (en) * 1959-10-05 1964-06-09 Automatic Elect Lab Loudspeaking telephone with electronic voice switching

Also Published As

Publication number Publication date Type
GB509693A (en) 1939-07-19 application

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