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telephone circuit schematics

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ahgu

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daa circuit

Anyone has a modern telephone circuit schematics, no transformer. as small as possible?

thanks
ahgu
 

ahgu

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telephone circuit basic

the name has been changed, and I don't see any single phone chip.
 

coppervaporlaser

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telephone line interface schematics

http://www.austriamicrosystems.com/0communications/phones/phones.htm :idea:

News:

Telecom Standard Products AS 2520 and AS 2521 phased-out
Demoboard AN 2201 for Single-Chip-Telephone (device AS 253x) passes EMC norm EN55024

Feature Phones

AS 2520/21 Handsfree telephone circuit - phased-out
AS 2522 Programmable handsfree telephone (succ. AS 2520/ 1) - new!
AS 2525 Single chip handsfree telephone (one die) + Download
AS 2591 LCD display driver with 32kHz osc

Basic Phones

AS 2533- 36 Single chip telephone (one die)
AS 2504 Speech circuit for CTs, TAM and fax
AS 2507 2-wire speech/ FSK intercom circuit

Webphones

Products will be available soon
[/url]
 

Rayengine

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french telephone circuit

ahgu said:
Anyone has a modern telephone circuit schematics, no transformer. as small as possible?

thanks
ahgu
What are the meaning modern telephone circuit? The transformer is for isolation which is safety issue and for some old ringer circuits. If you means featurephone, the marketing is already dominated by Taiwan source (Winbond, UMC ...)
 

ahgu

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old telephone circuits

How to design a DAA (phone line interface) without a transformer that does the coupling? from basic eletronic parts,

thanks
ahgu
 

Rayengine

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telephone circuit schemetics

ahgu said:
How to design a DAA (phone line interface) without a transformer that does the coupling? from basic eletronic parts,

thanks
ahgu

Again, the signal transformer is used for isolation and signal coupling in DAA circuit. If your design haven't any exposed metal, you wouldn't need any transformer. You just tape the signal from so-called audio in. You can found some design in Panasonic telephone service manual in Manual Database section.
 

papyaki

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how to design a telephone line interface circuit

Hi

Have a look at h**p://w*w.clare.com/Products/LITELINK.htm

They provide DAA for voice and data without transformer, but with optical isolation... See LITELINK III

Dont forget to look at h**p://w*w.clare.com/ They have other products for phone line designers
 

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