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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Phoneline to Soundcard - NEED HELP
Anyone know how-to make a cable that would plug into my telephone jack
and then into my computer soundcard? I bought one from EBay and when I plug the cable into my phone line and then into the soundcard my line goes dead. One guy mentioned he uses an isolator circuit of some sort to not short out the line in his device. This is the one I bought below that doesn't work. http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW ********** This one below supposedly works with a soundcard and phoneline. http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1 If you can help send an email to o m |
#3
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The unit at http://www.omnicronelectronics.com/PC/LIC-1PC.htm is more
appropriate for the OP, according to his stated problem. However, if the OP has the ability, there is a schematic of such a unit at http://www.solorb.com/elect/phone/tap. Another one with some good details at http://www.epanorama.net/documents/t...elerecord.html. The problem with the cable he bought on Ebay is that since there is no isolation, one side of the phone line is directly grounded to the computer case, which will indeed kill the phone line. The phone line must stay balanced and isolated from ground at all times, otherwise, the telco gets mighty upset. In fact, if you leave the line in a shorted condition, they will send a guy out to test your circuit, and if he finds the short exists inside your house, most likely the service will be disconnected until you remove the short. And they will charge you for the service incident. -- 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!! "Travis Jordan" wrote in message ... wrote: Anyone know how-to make a cable that would plug into my telephone jack and then into my computer soundcard? I bought one from EBay and when I plug the cable into my phone line and then into the soundcard my line goes dead. The one you bought probably works fine with an ac-isolated microcassette recorder with a high impedance microphone input. One guy mentioned he uses an isolator circuit of some sort to not short out the line in his device. 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.... http://www.omnicronelectronics.com/analog/LIC-100.htm |
#4
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DaveM wrote:
The unit at http://www.omnicronelectronics.com/PC/LIC-1PC.htm is more appropriate for the OP, according to his stated problem. However, if the OP has the ability, there is a schematic of such a unit at http://www.solorb.com/elect/phone/tap. Another one with some good details at http://www.epanorama.net/documents/t...elerecord.html. /analog/LIC-100.htm The zener diodes across the transformer secondary are a good idea. |
#5
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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 --------------- DaveM wrote: The unit at http://www.omnicronelectronics.com/PC/LIC-1PC.htm is more appropriate for the OP, according to his stated problem. However, if the OP has the ability, there is a schematic of such a unit at http://www.solorb.com/elect/phone/tap. Another one with some good details at http://www.epanorama.net/documents/t...elerecord.html. The problem with the cable he bought on Ebay is that since there is no isolation, one side of the phone line is directly grounded to the computer case, which will indeed kill the phone line. The phone line must stay balanced and isolated from ground at all times, otherwise, the telco gets mighty upset. In fact, if you leave the line in a shorted condition, they will send a guy out to test your circuit, and if he finds the short exists inside your house, most likely the service will be disconnected until you remove the short. And they will charge you for the service incident. |
#6
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Bill Jeffrey wrote:
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. True, but with good AGC you can compensate for this. |
#7
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"Bill Jeffrey" bravely wrote to "All" (13 May 05 10:29:49)
--- on the heady topic of " 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. |
#8
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In article fu5he.10093$D91.3759@fed1read01,
Bill Jeffrey wrote: 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. 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. -- Dave Plowman London SW To e-mail, change noise into sound. |
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