Phone Line to Audio

(Circuits -> Telephone)
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From: tpappas@hamp.hampshire.edu

We use telephone audio in our studio all the time. And yes, it's an off the shelf design. I designed and built such a device with scrap door components. I used an audio coupling transformer and a capacitor. The primary windings add in series to 500 ohms. Instead of connecting them directly together I added a cap between them. I think it was somthing like 0.047 micro farads with a 600vlt rating. And the secondary which is 500 ohms runs into the control room mixer.

           Tip   >------------/ II
                              / II /------------<
      (primary winding 1)     / II /
                              / II /
                 >-----X------/ II /
                       I        II /
         0.047 uF      =        II / -----------CT   (secondary winding)
                       I        II /
                >------X------/ II /                      Output Side
                              / II /                        to Mixer
      (primary winding 2)     / II /
                              / II /-------------<
        Ring    >-------------/ II

Try this circuit it works great for us in the studio. Just make sure you use properly rated components.


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