Ultimate Stereo VU Meter With Peak and Hold Using Arduino and Serial Shift Register

Due to some technical error on Instructables, I can't Upload much Media so I will update later as soon as Possible

Hey friend in this blog post I am making an Ultimate and Smooth VU Meter using Arduino and 74HC595 ICs (Integrated Circuit) or Serial Shift Register IC. It is a Stereo VU Meter which work with Two Analog Inputs for both Stereo Channels (Left and Right) and respond with the Analog Values by proper Map function to Decibels values on Arduino. It has 40 LEDs which respond to Analog Values corresponding to each LEDs. I saw a lots of VU Meter and try to make one but not every VU Meter is efficient and smooth and sometime blink and Haze effect, so I decided to make one by own which work like Studio Equipment type and also visualize like real Studio Audio Equipment’s like Amplifier, Audio Mixing Console, Microphone Tuner, Audio Interface, MIDI Controller and Many More (I also get the Idea from here and very curious for it, I like Audio DIY Stuff so Much so also stay tune with me and Subscribe my Channel). It enchase with the Peak and Hold feature, It show real time peak values for 1 second in each of the LEDs and slowly (1 sec time dependent) goes down to starting LED.

You can also enjoy with your Home Theatre or Home DJ System but please don't turn up the volume too much in excitement; otherwise, it could break the glass in other people's homes (If you have DJ in your home).  So let’s make it one.

My YouTube Video You can watch here and please Subscribe my channel also comments if you have any problem.

1x Arduino Microcontroller (Nano or Uno, etc. I recommend you to add ATMEGA328P-PU IC which is same IC use in Arduino common boards, it save lots of space in Circuit Board and easy to program).

8x 10 LED Segment bar Graph LED (Choose any of colours I use 2x Green means 20 LED for bottom, 1x Yellow means 10 LED for middle part and after 1x Red means 10 Red LED for top, You can choose what colour you want to choose).

10x 74HC595 IC Serial Shift Register (Always Solder with IC base for future troubleshooting or upgrades)

40x 220 Ohms Registers

1x PCB Board (Perf Board)

3x 2 Pin Connectors

1x 104J Capacitor

1x 1000uF or 470uF Capacitor 25V (Choose with your voltage fluctuations need)

Some Wires

Soldering Station and Tools

A VU (Volume Unit) meter is an audio measuring device that displays the signal level in audio equipment. It is typically used to indicate the loudness of audio signals, providing a visual representation of audio levels. The VU meter measures average levels, making it suitable for monitoring consistent audio signals. It helps audio engineers ensure audio signals remain within an optimal range, preventing distortion and maintaining audio quality.

VU meters consist of several components:

1. Input Stage: This receives the audio signal from the source.
2. Rectifier and Filter: The audio signal is rectified to convert AC signals into a DC signal that can be measured. A filter smooths the signal to eliminate rapid fluctuations.
3. Meter Movement: The processed signal drives a needle or LED display, indicating the signal level.

This project creates a stereo VU meter using an Arduino and 74HC595 shift registers to drive an 80-LED display (40 LEDs for each channel). Here's how it works:

1.    Audio Input: The audio signal is taken directly from the audio source (left and right channels). Each channel's audio signal is fed into separate analog pins (A0 for the left and A1 for the right) on the Arduino.

2.    Signal Conditioning: To stabilize the signal and reduce noise, each audio input is connected to a filter circuit with both analog inputs.

3.    Analog Reading: The Arduino reads the analog input values from A0 and A1. These values correspond to the amplitude of the audio signals.

4.    Peak Detection: The code includes a peak detection mechanism. It captures the highest value in a given period, emulating the "peak hold" feature found in traditional VU meters.

5.    Scaling and Mapping: The analog values are scaled and mapped to a range suitable for driving the LED display. This ensures that the LED levels correspond accurately to the audio signal levels.

6.    LED Display: The processed values are used to determine how many LEDs should light up. The Arduino uses the 74HC595 shift registers to control the LEDs. Each shift register controls 8 LEDs, allowing for efficient control of the 40-LED display. The LEDs light up in sequence, providing a visual representation of the audio levels.

7.    Peak Hold: The peak hold feature keeps the highest LED lit for a short duration, giving a visual indication of the highest audio level reached.

This Arduino-based VU meter project provides a visually appealing and functional way to monitor audio levels, enhancing the audio experience by providing real-time feedback on the audio signal's amplitude.

This is easy to build circuit diagram but many people find it difficult just by looking but actually not that is why also divided two parts of circuit diagram: - one is for the main VU Meter driver circuit and with LED Executions and the second part is the Adjustable Audio Filter Circuit which reduce unwanted noise.

Always remember that make sure the voltage level from input of Audio amplifier or etc sound equipment, due to this it can burn your Arduino or continuously reset which causes damage and add proper Capacitor with your Input specifications and Arduino 5V power line. After complete the circuit and double check everything, you can now add cords or wires for power and Inputs.

Now after all these steps you need to open Arduino IDE or if you have not so download from here www.Arduino.cc then install it.

Copy the whole code from here and paste it to your Arduino IDE and Select the Com Port and Board.

Here- Code

Now you can rock and shock everyone! If you have a big amplifier (e.g., 50W, 100W, 150W, 2000W, and so on), make sure to always check the input voltage level. Adjust the input variable for precise tuning of the LED levels to sync perfectly with your audio or music.