Title: Line matching circuit for use in a tone pushbutton dialling subscriber's set provided with a tone generator

Abstract: An impedance matching circuit for a pushbutton telephone uses two voltage regulating transistors having their emitter-collector terminals connected in parallel with a potentiometer, the output terminals of the telephone set, and the output of a pushbutton tone generator amplifier. The base terminal of one of the transistors is connected directly to a tap of the potentiometer, while the base of the second transistor is connected to a further tap on the potentiometer through a low pass filter.

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Inventors: Janssen, Daniel Johannes Gerardus (Eindhoven, NL)
Hart, Cornelis Maria (Eindhoven, NL)

Application Number: 472284
Filing Date: 1974-05-22
Publication_date: 1976-09-21
Assignee: U.S. Philips Corporation (New York, NY)
Primary Class(es): 379/394
Other Classes:
US Patent Ref:

3731004	May, 1973	Coupland	179/84.
3823272	Jul, 1974	Tabalba	179/81.

Other Refs:
Primary Examiner: Claffy, Kathleen H.
Assistant Examiner: Popek, Joseph
Attorney: Trifari; Frank R., Cohen; Simon L.