Penetration Testing mailing list archives
Re: blind demodulation - sound card - lucent winmodem - new topics
From: "Ian Charnas" <icc () po cwru edu>
Date: Fri, 5 Jul 2002 00:18:02 -0400
Could anybody having enough knowledge on electronic circuits send me a
circuit
diagram so that i can connect my phone line to the line-in of my sound
card? If
i can do this, i would be very glad and continue to try to code the dsp
stuff. Yes - http://www.iancharnas.com/docs/projects/telephone-recorder/telephone-circuit .gif The capacitor is there to block the DC (voice comes through on AC). The 600:600 transformer is the most important piece, it provides electrical isolation between the telephone and your sound card. The zener diodes are there to protect your sound card from the high voltages seen when your phone rings. All these pieces can be bought at radio shack, or any decent electronics store. A few notes: 1. Do *NOT* use one of the shoddy Radio Shack telephone recorders. First of all they do not provide electrical isolation between your sound card and your telephone line (no transformer, only diodes and resistors), and second of all the impedence is not matched to your sound card and you will get a ridiculously loud hum, which would make your project that much tougher. 2. Do *NOT* merely use a transformer. As your telephone starts to ring, the high voltage generated in the secondary winding will kill your A/D device (sound card?). Hope this helps -Ian Charnas ---------------------------------------------------------------------------- This list is provided by the SecurityFocus Security Intelligence Alert (SIA) Service. For more information on SecurityFocus' SIA service which automatically alerts you to the latest security vulnerabilities please see: https://alerts.securityfocus.com/
Current thread:
- Re: blind demodulation - sound card - lucent winmodem - new topics Evrim ULU (Jul 02)
- Re: blind demodulation - sound card - lucent winmodem - new topics Deus, Attonbitus (Jul 03)
- Re: blind demodulation - sound card - lucent winmodem - new topics Ian Charnas (Jul 05)
- <Possible follow-ups>
- RE: blind demodulation - sound card - lucent winmodem - new topics Jay Stapleton (Jul 03)
- RE: blind demodulation - sound card - lucent winmodem - new topics Jay Stapleton (Jul 05)
- Re: blind demodulation - sound card - lucent winmodem - new topics Evrim ULU (Jul 07)
- Re: blind demodulation - sound card - lucent winmodem - new topics Neil mccauley (Jul 08)
- Re: blind demodulation - sound card - lucent winmodem - new topics Evrim ULU (Jul 07)