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Author Topic: Arduino turned on, the sound have distortion  (Read 541 times)
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Hello, i've made a simple VU Meter and, to the input of sound to arduino, i've used a simple 3.5mm connector cable. The arduino reads the voltage of the output of headphones from the computer to the analog input.

The problem is: i'm using a small adapter to connect 2 sound system to my headphones output on my laptop, here there is no problem. The problem appears when i connect 1 sound system and the cable to arduino. When i connect the cable to arduino in the adapter, the sound of my sound system starts to have a little distortion.

Someone can help me to discover why is distortion created when i turn on arduino or connect the cable to it? The arduino should only reads the voltage of the sound incoming from the cable and not add some distortion to it because i'm sending nothing to the analog input of arduino, only receiving the information through it.

Thanks in advance,

Luís Geraldes

P. S. --> if I'm not understandable, please say.
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The arduino should only reads the voltage of the sound incoming from the cable and not add some distortion to it because i'm sending nothing to the analog input of arduino, only receiving the information through it.
Not quite, arduino also presents a load to the signal source. You can minimize effect, simply inserting a resistor in series with arduino input, 1 - 10 k. More info on your hardware set-up would be necessary to provide more accurate advise.
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think about a simple buffer isolating the arduino from the audio source. any dual opamp is probably the easiest solution.
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Not quite, arduino also presents a load to the signal source. You can minimize effect, simply inserting a resistor in series with arduino input, 1 - 10 k. More info on your hardware set-up would be necessary to provide more accurate advise.

Thanks, i'll try that. Higher the resistor, probably less distortion, right?
One more thing, with the resistor, the signal of the sound will be exactly the same? I mean, same properties?
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think about a simple buffer isolating the arduino from the audio source. any dual opamp is probably the easiest solution.

Can you explain me a little more? And tive me an example of one dual opamp in, for example on sparkfun.com?

Thanks!
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