VU Meter Lightshow

Anh Hoang

Issue 47, June 2021

This small device produces a strip of LEDs that lights up accordingly to the volume of the sound it is playing. We got in touch with its designer, Anh to find out more.

Fun little project you made, Anh. Before we talk more about it, tell our readers a little about yourself.

Hi, my name is Anh Hoang. I am a Vietnamese international student studying Year 12 in Sydney, Australia. I aim to study Mechatronics Engineering at UTS.

Before building DIY gadgets and machines, I am a LEGO enthusiast and even had my own LEGO YouTube channel. I built functioning LEGO guns that shoot rubber bands and LEGO bricks (don't worry, no one was hurt hahaha).

I have been building working DIY models since Year 6 and have completed 30+ models ranging from simple mechanical actuators such as a DC water pump or a Vacuum Cleaner to recently more complicated models that require Arduino, such as an Automatic Hand-sanitiser Dispenser. I am also a basketball player and love the piano.

LEGO is a great way to get into mechatronics when Technic is involved. What got you interested in electronics, Arduino and coding?

Although LEGO will always have a special place in my heart, I recognised the application it poses is not really practical. This is why I found creators on YouTube such as The Hacksmith, Colin Furze, Adam Savage.

I fell in love with the amazing things they can build and the more practical properties they propose. I have always been curious in everything I see in terms of how they work. It is the combination of these things that drew me into the world of DIY building.

The things those guys make can be mind blowing. What motivated you to build your project?

It is honestly just the curiosity in how gadgets work and in knowing my limits as a builder and creator. A lot of the time I build gadgets and models as the way to test and broaden my knowledge and to see how far behind I am compared to the DIY Electronics hobbyist community.

That’s great. Even just tinkering is a good way to learn. How does your VU meter work and what parts does it use?

This project consists of two parts: the speaker and the light show that corresponds to the speaker.

The first part is rather simple. It is just a Bluetooth Amplifier Module that is powered by USB 5V that outputs a small 4 Ohms 3 Watt Speaker Driver.

The second part is where a bit of electrical knowledge comes to play. I have included a circuit diagram that I drew. Basically, the whole circuit does not need any IC like the 555 Timer. Instead, it just simply uses the AC audio signal directly from the Amplifier Module. As each "wavelength" gets sent to the circuit, that voltage lights up a certain number of LEDs depending on if it's high or low voltage. The higher the voltage from the audio signal, the more LEDs it lights up. This is how the light show corresponds to the music that is being played.

ElectroParts Required:
6 x LEDs
6 x 330Ω Resistors
2 x 1N4007 Diodes
2 x 470µF Capacitors
4 x 1N4148 Small Signal Diodes
1 x 3W 4 Ohm Speaker Driver
1 x Bluetooth Amplifier Module (either DIY or buy)
1 x USB 5V Power Supply (or a regulated 5V power supply)

ElectroParts Required:

You can continue to add more LEDs, diodes and resistors to have 4, 5 ,6 etc number of LEDs but they will get dimmer and dimmer as the number increases.

What design challenges did you need to overcome?

It was mainly the finding of a good diffuser material. All the acrylic pipe I tried was not sufficient. I found hotglue sticks to be much better. Surprisingly, hotglue sticks are great light diffuser, and the LEDs snuggly fit inside the sticks.

That’s resourceful. Is that a jiffy box you have used as the enclosure?

Yes, indeed.

If you were to build it again, would you do anything differently?

I would probably build a more powerful Bluetooth Amplifier circuit that outputs a stronger audio signal. This will allow me to light up more LEDs, and thus create a longer and more entertaining light show.

Is there anything we haven't discussed that our readers should know about?

Follow your passion!

What are you working on next?

An Arduino based PID pencil balancer.

Sounds like a fun challenge. Thanks for sharing your project with our readers.

Anh Hoang

Anh Hoang

Year 12 student, Australia.