# Headphone Jack questions

**URL:** <https://forum.clockworkpi.com/t/headphone-jack-questions/18538>\
**Category:** PicoCalc\
**Tags:** hardware, programs\
**Created:** [July 11, 2025, 11:25am UTC](https://forum.clockworkpi.com/t/headphone-jack-questions/18538 "2025-07-11T11:25:53Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![M57](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/m57/32/12528_2.png) [@M57](https://forum.clockworkpi.com/u/M57)\
**Post date:** [July 11, 2025, 11:25am UTC](https://forum.clockworkpi.com/t/headphone-jack-questions/18538/1 "2025-07-11T11:25:53Z")

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So, I was scrolling through youtube shorts last night and came across someone using the headphone jack with a rp2040 chip to visualize audio input? Is the Picocalc capable of this?

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**Author:** ![JackCarterSmith](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/jackcartersmith/32/11509_2.png) [@JackCarterSmith](https://forum.clockworkpi.com/u/JackCarterSmith)\
**Post date:** [July 11, 2025, 10:36pm UTC](https://forum.clockworkpi.com/t/headphone-jack-questions/18538/2 "2025-07-11T22:36:46Z")

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Hi,

I’m not sure but the audio circuitery use a NC7WZ16 buffer chip (U501) to “adapt” and protect the pico IO from the filter/output side.  
You can’t read any analog signal from the outside using the jack port or the speakers.

Maybe you can use external mic on the side GPIO instead?

EDIT: another “hard” way should be to add an another buffer reversed and connect the output on a free IO pin of the pico. But we are entering the realm of surgery at this point…

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<div class="post-metadata">

**Author:** ![pelrun](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/pelrun/32/12323_2.png) [@pelrun](https://forum.clockworkpi.com/u/pelrun)\
**Post date:** [July 12, 2025, 4:28am UTC](https://forum.clockworkpi.com/t/headphone-jack-questions/18538/3 "2025-07-12T04:28:33Z")

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You just need to get the audio delivered to an adc pin on the Pico - as Jack has stated, you can use the GPIO on the side for this (GPIO28 is A2). You need some circuitry to appropriately bias the input as audio signals are bipolar (both positive and negative voltage) but the ADC is positive voltage only; a capacitor and a couple of bias resistors to 0v and 3.3v is the minimum circuit to do that. After that it’s just a matter of software.