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I want to feed Audio input (music played in my phone or laptop) to Arduino using an AUX cable(3.5 mm).

I know that we need to offset and amplify the signals as the Arduino takes input from 0 to 5v and the signals are very small.

I really searched all over the internet but couldn't find any step by step or basic stuff.

Please help !!

P.S. - I am not very mature in the field of electronics.

Thanks

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  1. Amplify the signal so that peak-to-peak voltage is within 5V but high enough for it to be meaningful to the Arduino. You can use an op-amp based amplifier using the inverting or non-inverting configurations. Look at the inverting and non-inverting amplifiers here: https://en.wikipedia.org/wiki/Operational_amplifier_applications#Amplifiers

  2. Offset the voltage. This can be as simple as AC coupling the output and using a voltage divider to create the offset. Creating DC offset

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  • \$\begingroup\$ Can you help me with the real basics !! Like parts to be used and circuits ! I really need this but can't figure out what do Thanks ! \$\endgroup\$ – Parth Jeet Jan 17 '16 at 20:00
  • \$\begingroup\$ I've updated my answer to add more details. That should get you going. \$\endgroup\$ – Tahmid Jan 17 '16 at 20:05
  • \$\begingroup\$ Which one of the amplification circuit would you prefer to use -- Inverting, Non-inverting or the differential ? \$\endgroup\$ – Parth Jeet Jan 17 '16 at 20:09
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You can use an inverting configuration off a single rail power supply to both amplify the signal and have a DC offset.

Single rail inverting amplifier

Look here:http://www.radio-electronics.com/info/circuits/opamp_inverting/op_amp_inverting.php

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  • \$\begingroup\$ I Tried implementing the circuit using Pspice simulation. I am not getting it. Can u give me a hint on the values of the resistors and the capacitors ? \$\endgroup\$ – Parth Jeet Jan 17 '16 at 21:31
  • \$\begingroup\$ From the link I added: "This can be achieved by biasing the input of the op amp at half the rail voltage and then having decoupling to ground where necessary and inter-stage coupling to remove any DC voltages." "The Single rail inverting amplifier circuit is relatively straightforward. The operating point is set by the two resistors R3 and R4. C4 provides the decoupling to earth or ground and should offer a low impedance at the lowest frequency of operation." The link also mentions how to select the values. You can use 100kΩ for R3 and R4. R2/R1 sets the gain. What values did you try? \$\endgroup\$ – Tahmid Jan 17 '16 at 23:47

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