I am currently able to feed a 3.5 mm aux cable into my Arduino and read its values, but I'm not able to hear the sounds being played. I wanted to solve this problem by using an audio splitter and adding speakers. However, when I read values from my 3.5 mm aux cable attached to the audio splitter, I'm only getting 0s. How can I fix this problem?

Edit: Without the audio splitter (Arduino can read values from aux cable): enter image description here

With the audio splitter (Arduino can't read values from aux cable): enter image description here

The source of the audio is from my laptop and it is a stereo signal. The splitter is also has a stereo signal. The Arduino is reading the signal in the A0 port and its being powered from my laptop.

  • 1
    \$\begingroup\$ You should really add a diagram. It helps us help you. Also add as many details as possible. What is the source of audio, your phone/car? Is this a stereo, or mono signal? Is your splitter stereo, mono, or you don't know? What ports are you using on the Arduino? How is it being powered? Etc etc. As is, your question is vague and your issue is thus difficult to troubleshoot. We are forced to guess what is happening. \$\endgroup\$
    – Bort
    Commented May 8, 2018 at 18:56
  • \$\begingroup\$ Sorry about that, I'm pretty new to these things so I wasn't sure what information to add, but I made changes that I hope answer your questions. If there's anything else you need to know, ask away. Thanks! \$\endgroup\$
    – David Tran
    Commented May 8, 2018 at 19:49
  • \$\begingroup\$ does it work w/o the speakers plugged in, but w/splitter? if not, bad splitter. if so, a too low impedance on the speaker \$\endgroup\$
    – dandavis
    Commented May 9, 2018 at 3:38

1 Answer 1


From what you've described I can think of two possible issues:

1) If the audio splitter stops the Arduino from reading values even when the speakers are not connected to the splitter, then you have a dodgy splitter (simple enough).

Try verifying your splitter by checking the resistance between pins at either end, including your additional cable. If there is an open circuit this will be very apparent.

2) If the drop-out only occurs when you add the speakers, you are loading the headphone output of your laptop and that is dropping the voltage to beneath what you can measure.

From a quick bit of googling I found that some basic PC speakers have an input impedance of around 10 kΩ. Presuming you are using the analogue input pins on the Uno, they have a very high input impedance of around 100 MΩ.

Given these numbers I would actually find excessive loading to be a bit surprising as headphone outputs are intended to drive much lower impedances, down to around 32 Ω.

Do check out your splitter and report back!


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