phone line level to microphone input

--DF

In article , snipped-for-privacy@def.net (known to some as D. G.) scribed...

You would do well to consider that most phone companies are still picky about what gets hooked up to their lines, and that ringing voltage is on the order of 90-100VAC at 20Hz, and get yourself a proper voice coupler. Such a device will protect you and your equipment.

Have a look at this page:

Happy hunting.

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
http://www.bluefeathertech.com -- kyrrin a/t bluefeathertech d-o=t calm
"Salvadore Dali\'s computer has surreal ports..."

It seems the full signal or may be half of it is fed into the microphone input in this design. Strange! I would fear it can overload the input or be more compatible with a LINE level input... Coincidence, what I'm building is for the same purpose (for VoIP) but I use a 600 ohm transfo for the hybrid circuit. The design at

cannot work on my system as the mic and the speaker share the same ground :(

Dan

be

use

cannot

BTW -10dBm translates to 245 mVrms into 600 ohms: 10*log10(PmW/1mW)

--DF

Oops! I was using 20*log() equation.

Thanks for the link at

I quickly built the first circuit showed on that web page but I replaced the mic input by a small traff (primary) to isolate ground. Then I connected the mic input at the traff (secondary) through a 22K/220 divider. Perfect!

Regards! Dan

Another simple solution

RS232 solution is

I fear you have posted an incorrect link. What has IRMeasure to do with adapting a phone line to a computer sound card input?