This is my submission for the Make-to-Learn Youth Contest:
What did you make?
I made an old style analog VU meter and Clock using 2 analog panel meters, an Arduino, a real time clock, and other simple components. How it works: The unit plugs into a standard 3.5mm speaker jack. The Arduino reads the sound levels and converts it into electric pulses (PWM) to control the analog meters. When no sound is detected, the unit automatically changes to Clock mode and displays the time which is read from the real time clock circuit.
How did you make it?
I got the idea to make an analog VU meter from seeing them used in older audio receivers and amplifiers. I was always intrigued by the effect of a needle “dancing” to the beat of music. With my basic knowledge of electronics and the Arduino platform, I decided that I could make one myself. After searching around the internet to see if anyone had done anything similar, I found that many people create Clocks with analog panel meters. Well, why not include both functions?
Where did you make it?
I made this at home by myself. I like to listen to music a lot and I am always tinkering and playing with electronics. I thought that this would be a fun project to compliment my speaker system which I also built myself.
What did you learn?
I learned a lot from this project. The hardest thing to get right was the programming. I have never worked with analog panel meters before, so getting them to display time and sound accurately was challenging. For example: It was hard to get both meters to point exactly straight up at 6:30. I also learned that connecting the Arduino directly to an audio source can distort the audio. To fix this, I added some resistors and the distortion went away.
Video:
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Signing UpStep 1: Materials
- 2, 5v Analog panel meters (Amazon) or (Amazon)
- Arduino (I used the pro mini) (Amazon)
- DS1307 Real time clock (Amazon)
- Protoboard (Amazon)
- 10K potentiometer (DigiKey)
- 2 tactile switches (DigiKey)
- 4 10K resistors (DigiKey)
- 4 white LEDs (optional) (DigiKey)
- USB cable (DigiKey)
- 3.5mm cable (DigiKey)
Total cost is around $47. It will be less if you have some of these parts already.



































![Mini Arduino PC [Eng-Ita] How To & Code](http://www.instructables.com/files/deriv/FVH/UYPD/HFSHFS2V/FVHUYPDHFSHFS2V.SQUARE.jpg)





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Any thoughts? The serial monitor shows the time is incrementing and decrementing correctly when the appropriate up or down button is pressed. Also the
The meters go high, then low during the startup as they should.
analogWrite(leftMeter, -X) Where x is the chosen value for each instance
---also include negative as shown here----
if (minutes * -4.75 < 255){ // increase PWM value by 4.75 each minute
analogWrite(rightMeter, minutes * -4.75)
I want to give thanks to the author as well. He inspired me to do my own version. Thanks.
One thing that would be nice, If an estimate of cost on projects, I've been wanting to make one of these but the cost is what's stopping me.