Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M19/00—Current supply arrangements for telephone systems
  • H04M19/02—Current supply arrangements for telephone systems providing ringing current or supervisory tones, e.g. dialling tone or busy tone
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
  • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
  • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
  • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
  • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
  • C07D239/47—One nitrogen atom and one oxygen or sulfur atom, e.g. cytosine
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
  • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
  • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
  • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
  • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
  • C07D239/48—Two nitrogen atoms
  • C07D239/49—Two nitrogen atoms with an aralkyl radical, or substituted aralkyl radical, attached in position 5, e.g. trimethoprim
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J3/00—Time-division multiplex systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J3/00—Time-division multiplex systems
  • H04J3/02—Details
  • H04J3/04—Distributors combined with modulators or demodulators
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M3/00—Automatic or semi-automatic exchanges
  • H04M3/22—Arrangements for supervision, monitoring or testing
  • H04M3/24—Arrangements for supervision, monitoring or testing with provision for checking the normal operation

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Testing Electric Properties And Detecting Electric Faults (AREA)
• Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
• Amplifiers (AREA)
• Electrotherapy Devices (AREA)
• Rectifiers (AREA)
• Emergency Protection Circuit Devices (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=6626875

Family Applications (2)

Family Applications Before (1)

Country Status (5)

Families Citing this family (4)

Family Cites Families (3)

• 1951
  • 1951-08-13 DE DES24396A patent/DE897853C/de not_active Expired
• 1952
  • 1952-07-30 US US30164752 patent/US2747023A/en not_active Expired - Lifetime
  • 1952-08-05 FR FR1090934D patent/FR1090934A/fr not_active Expired
  • 1952-08-13 BE BE513500D patent/BE513500A/xx unknown
  • 1952-08-13 GB GB2036152A patent/GB718155A/en not_active Expired
• 1955
  • 1955-02-08 DE DES42610A patent/DE951458C/de not_active Expired
• 1956
  • 1956-02-06 FR FR69952D patent/FR69952E/fr not_active Expired
  • 1956-02-07 BE BE545026D patent/BE545026A/xx unknown

Also Published As

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