GB869895A - Improvements relating to communication apparatus - Google Patents
Improvements relating to communication apparatusInfo
- Publication number
- GB869895A GB869895A GB3199956A GB3199956A GB869895A GB 869895 A GB869895 A GB 869895A GB 3199956 A GB3199956 A GB 3199956A GB 3199956 A GB3199956 A GB 3199956A GB 869895 A GB869895 A GB 869895A
- Authority
- GB
- United Kingdom
- Prior art keywords
- loud
- switch
- speaker
- amplifier
- microphone
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R27/00—Public address systems
- H04R27/04—Electric megaphones
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Burglar Alarm Systems (AREA)
- Fire Alarms (AREA)
- Alarm Systems (AREA)
Abstract
869,895. Loud-speaker systems. FORESIGHT PRODUCTIONS Ltd. Jan. 20, 1958 [Oct. 20, 1956], No. 31999/56. Class 40 (4). Loud-hailing and intercommunication equipment carried by a fireman includes a throat contact microphone 12 and a portable case 15 housing an amplifier and a loud-speaker 20. The equipment is linked to a remote station by a cable Ca which may also serve as a smoke line. Calling signals and alarm signals can be made. Microphone.-A contact microphone comprises two elements carried by a collar 13 of rod, tube or strip material which may be sprung into position. Sponge rubber covers prevent acoustic reaction. Amplifier circuits &c. (Provisional drawing).-With switch S2 closed and S1 as shown, the microphone MIC is linked to the loud-speaker SP 1 by a three-stage transistor amplifier. An alarm signal is given by a buzzer on closing switch S3. The loud-speaker SP1 is connected in parallel with a loud-speaker SP2 at a remote station over cable Ca. Loud-speaker SP2 also serves as a microphone. Switch S4 connects a buzzer to give a calling signal. Switch S1 is changed over to receive and amplify speech from the remote station. In an alternative circuit, Fig. 4, the loud-speakers SP1, SP2 and the output transformer secondaries at two similar stations are connected in series over the cable so that both loudspeakers reproduce the signals from microphones at either station. Thermionic valves V1, V2 are used for the first two amplifier stages. When switch S3 is operated, they oscillate to generate an alarm signal. Switch S2 is the amplifier on/off switch.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3199956A GB869895A (en) | 1956-10-20 | 1956-10-20 | Improvements relating to communication apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3199956A GB869895A (en) | 1956-10-20 | 1956-10-20 | Improvements relating to communication apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
GB869895A true GB869895A (en) | 1961-06-07 |
Family
ID=10331507
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB3199956A Expired GB869895A (en) | 1956-10-20 | 1956-10-20 | Improvements relating to communication apparatus |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB869895A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4311872A (en) * | 1979-05-21 | 1982-01-19 | Davis Robert P | Portable voice communication system |
GB2165721A (en) * | 1984-10-16 | 1986-04-16 | Charles William Dickinson | A speech facility for a facemask |
-
1956
- 1956-10-20 GB GB3199956A patent/GB869895A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4311872A (en) * | 1979-05-21 | 1982-01-19 | Davis Robert P | Portable voice communication system |
GB2165721A (en) * | 1984-10-16 | 1986-04-16 | Charles William Dickinson | A speech facility for a facemask |
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