Phoneline to Soundcard - NEED HELP

The one you bought probably works fine with an ac-isolated microcassette recorder with a high impedance microphone input.

Yep, that would be a good idea.

Personally, I'd build such a device with a couple of .1 mfd coupling capacitors and a 600 ohm to 600 ohm isolation transformer to provide a balanced input. Total parts cost about $5.00. However, if you need to buy one then....

The unit at

-- Dave M MasonDG44 at comcast dot net (Just subsitute the appropriate characters in the address)

Never take a laxative and a sleeping pill at the same time!!

The zener diodes across the transformer secondary are a good idea.

I've tried this (coupling to the phone line) a couple times, without real good luck. The problem I experienced is that the outgoing audio is MUCH louder than the incoming audio. Kinda makes sense, since the outgoing audio will undergo line loss before it get to the other end, whereas the incoming audio has already undergone that loss.

Question: has anyone else found this to be true? And if so, would it make sense to take the tap at the earpiece in handset instead of across the line? The incoming audio is present at the earpiece, of course - and so is the outgoing audio, in the form of sidetone, which is carefully set up to have the same apparent loudness.

BTW, if you have an old Bell phone (the hefty ones, like the 302), it is easy to monitor it without making any connection. Simply place an audio transformer on the case, and connect one of the windings to the mic input of the recorder/sound card. The transformer picks up the audio from the induction coil inside the phone. We used to do this in the old old days, using the output transformer from any old radio. Of course it won't work in modern lightweight phones, since they have no coil inside.

Bill

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DaveM wrote:

True, but with good AGC you can compensate for this.

"Bill Jeffrey" bravely wrote to "All" (13 May 05 10:29:49) --- on the heady topic of "Re: Phoneline to Soundcard - NEED HELP"

BJ> From: Bill Jeffrey BJ> Xref: aeinews sci.electronics.repair:48060

BJ> I've tried this (coupling to the phone line) a couple times, without BJ> real good luck. The problem I experienced is that the outgoing audio BJ> is MUCH louder than the incoming audio. Kinda makes sense, since the BJ> outgoing audio will undergo line loss before it get to the other end, BJ> whereas the incoming audio has already undergone that loss.

BJ> Question: has anyone else found this to be true? And if so, would it BJ> make sense to take the tap at the earpiece in handset instead of BJ> across the line? The incoming audio is present at the earpiece, of BJ> course - and so is the outgoing audio, in the form of sidetone, which BJ> is carefully set up to have the same apparent loudness.

BJ> BTW, if you have an old Bell phone (the hefty ones, like the 302), it BJ> is easy to monitor it without making any connection. Simply place an BJ> audio transformer on the case, and connect one of the windings to the BJ> mic input of the recorder/sound card. The transformer picks up the BJ> audio from the induction coil inside the phone. We used to do this in BJ> the old old days, using the output transformer from any old radio. Of BJ> course it won't work in modern lightweight phones, since they have no BJ> coil inside.

What you need is a hybrid phone network. Basically it balances the voice so that it has the same volume as the speaker. Older phones used a transformer to balance the levels. New phones use an IC instead. Another trick is to clip onto the speaker of a speaker-phone.

A*s*i*m*o*v

... I worked hard to attach the electrodes to it.

You need a TBU - telephone balance unit - to correct this properly. They're used to connect a telephone line to a broadcast sound mixing desk

- etc. Basically, a hybrid transformer or electronic equivalent. This convert the two wire telephone circuit to a four wire so you can adjust in and out levels, IIRC.