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Publication of BE522174ApublicationCriticalpatent/BE522174A/xx
H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
H03B5/20—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator
H03B5/22—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator active element in amplifier being vacuum tube
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