audioguru
Nobel Prize Winner
    
Canada
4218 Posts |
Posted - Apr 15 2010 : 9:54:03 PM
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You found an extremely simple circuit. Most extremely simple circuits work poorly.
In Canada, the phone network runs off 48V to 50V, not 12V. A phone draws enough current to drop it to about 8V. If the circuit does not limit the current then the phones might burn up. A phone line does not use resistors that reduce the levels, instead it uses transformers that pass audio without loss and pass DC to the phones. |
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