I’ve always wanted to do this, and finally rigged one up! It consists of a 99 neopixel strip from adafruit, a scavenged 3.5mm audio cable, an adruino UNO, alligator clips, jumper wires, a power supply, and an output jack for speakers or headphones. An analog arduino pin is connected directly to the right channel, the grounds are common, and the signal wires just pass through to the output jack uninterrupted. Here’s the circuit:

VUMETERCIRCUITThe gif doesn’t give it justice, neither do the pictures. The color is rich and impossible to photograph, and the falling dot at the top is pushed up by the max level and falls at about 6 pixels/second back down to the current level. It’s very fast and is smooth in transitioning from the different levels. Here it is!

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The arduino sketch:

VUMETER

99 Neopixel VU Meter!
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10 thoughts on “99 Neopixel VU Meter!

  • July 14, 2014 at 4:06 PM
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    I tried to use a 8 neopixel strip, but it doesn’t work… It just get a rainbow color on the strip….anything moove . I connect the MIC on the A0 input

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    • July 16, 2014 at 8:59 AM
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      Did you change the number of LEDs in the strip towards the top of the code to 8 from 99? I’ll have a look at it, rewrite it to 8, and post it for you.
      -John

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  • August 1, 2014 at 12:37 PM
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    Hi this looks exactly like what I’m trying to make, is it possible for you to please show a larger picture of the connections? Pretty new to this so I’m somewhat guessing. I think I have it pretty close but it’s not working right yet. Thanks!

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    • August 1, 2014 at 12:57 PM
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      Hi Jerry! What I mean by the signal wires is exactly that: the right and left signals coming from your audio cable. All the arduino does is add a sense pin to the uninterrupted audio signal from your device on one of the channels to you speakers or headphones and get an analog reading from it. I’ll make a diagram and add it to the page for you.
      -John

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    • August 1, 2014 at 1:21 PM
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      There you go! The diagram’s up! Make sure to show me some pictures when you get it running!

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  • August 1, 2014 at 3:36 PM
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    Hey you’re awesome! Going to try again, BRB.

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  • August 1, 2014 at 4:23 PM
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    Hi John, it works great 🙂 http://i.imgur.com/BkS3rQ2.jpg

    I didn’t understand at first that the audio cable ground had to be a connection as well, the diagram helped greatly. I kept looking for hours for a simple VU that didn’t involve a mic or more parts, so glad I found your guide. Thanks!

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    • August 3, 2014 at 10:28 AM
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      You’re very welcome! I’m glad I could help! The black strip looks awesome! 🙂

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      • October 28, 2014 at 7:13 PM
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        Hi John ,excuse me for my english but i come from Belgium and i speak French.My question is : is it possible to drive two led strip rgb to make a stéréo Neopixel Vu meter one for the left channel and one for the right channel ?What is the diagram and what must i add to the arduino code ?Thank you verry much

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        • November 4, 2014 at 4:41 PM
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          Hi Denis! That’s possible and a great idea! I don’t know how much programming experience you have, but all it would involve is another led strip object with a different name connected to a different signal pin but the same power and ground connections. You’d also need the other channel connected to an analog pin, and to duplicate the code needed to write to the leds and modify it to use the new led and audio pins. If you have any further questions, I’ll be happy to help you further!

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