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landline telephone voltage

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encoder

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Is land line telephone has a particular operating voltage.
 

Yes. they feed 48 to 54 V Dc with a current limit of 25 to 35mA for phone working. For rining , they feed 50 to 75V 25/50Hz AC superimposed on the DC voltage mentioned above.
 

For rining , they feed 50 to 75V 25/50Hz AC superimposed on the DC voltage mentioned above.
and for the voice communications, that is simply a lower voltage AC signal superimposed on the line.
When a connection between the 2 telephones is made, and current is drawn, then the DC voltage drops to just a few volts.
However please note that dangerously high voltages can appear on the traditional, old, landlines which travel long distances in the open air, including pulses from lightning which may be poorly captured by the protection installed at the switches/exchanges.
 

as per any standard , it might be positive ground. As per Telecom bibles, a positive grounded supply on the olden days open wire lines, helps to save copper wires from electrolytic action between the ground and the other wire, atmosphere acting as electrolyte.
Earlier designs have slowly disintegrated copper wires. then the technology had been changed to positive ground. most telecom installations across world follow this as a principle, including AT&T and many other American digital switches.
 

Is land line telephone has a particular operating voltage.

Operating voltage usually refers to off-hook voltage.
Also depends on your telephone circuits but it works at around 6.5V to 12V.

:)
 

the idea of feeding a voltage some where between 48 to 52 is that the phones have to work for a distance of say 4 to 5Km. Including the line resistance, and the impedance of the battery feed circuit of the central office and that of instrument itself, to drive a 25 to 30mA of DC current for proper operation, such high voltage is needed.
 

in electromechanical exchanges the ringing current is super-imposed on the dc. Later, in electronic exchange era some designs feed ringing alone and battery feed during ring pause periods.
 

its nice but if my phone in ideal mode then what is the power consumption..
**broken link removed**
 

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