LED Vu-Meter with Microphone LM3915 & LM386 - PCB Tutorial

This Vu-Meter with LM3915 integrates an LM386 amplifier and a microphone, so that it can work without having to be physically connected to any audio source. As LED display I used a bargraph (Model: KYX-B10G). The sensitivity of the microgon (GAIN) is adjustable by means of a 10KΩ trimmer placed on the PCB. The Vu-Meter must be powered with a voltage between 5v and 12v DC, and the maximum current absorption is equal to 100mAh. There is also a 1N4007 diode in the circuit which protects the Vu-Meter from short circuits during power supply phase.

● Components:
1x LM3915 IC
1x LM386 IC
1x 10 LED Bargraph (Model: KYX-B10G)*
1x Microphone Capsule
1x 3mm LED (any color)
1x DIP 18 PIN (for LM3915)
1x DIP 8 PIN (for LM386)
1x 1uF Electrolytic Capacitor (25-100v)
2x 10uF Electrolytic Capacitor (25-100v)
1x 100uF Electrolytic Capacitor (25-100v)
1x 10nF Polyester Capacitor
1x 47nF Ceramic Capacitor
2x 1N4007 Diode
1x 50Ω ¼W Resistor
1x 1KΩ ¼W Resistor
3x 2,7KΩ ¼W Resistors
2x 100KΩ ¼W Resistors
1x 10KΩ Trimmer
1x 9V battery Plug (or two PIN/wires)
1x Two PIN for Dot/Bar Mode
1x PIN Bridge with two PIN
1x Trimmer knob (not mandatory)

* I used a 10 Green LED Bargraph (Model: KYX-B10G) but you can use a Bargraph of different colors, as long as it respects the pinouts of this model.

● Equipment:
- Tin Wire (with integrated flux)
- FLUX (extra FLUX if you need to use it)
- Soldering Iron
- Wire cutters

*Don't use my PCB for profit or sponsored videos.

● Features:
Range: 30dB (3dB for LED)
Power Supply: 9-12v DC
Absorbed current (MAX): 100mA/h
Weight (assembled): 20g
PCB Layer: 2
PCB Size: 33x67 mm
PCB Thickness: 1,6 mm
Screw fixing holes: 4x 2 mm
Short circuit protection: YES (with a 1N4007 Diode)
Cool design: YES
Adjustable GAIN (by 10KΩ Trimmer)

- About LM3915:
LM3915 is a monolithic integrated circuit that detects analog voltage levels and drive ten LEDs, LCDs or vacuum fluorescent displays, supplying a logarithmic 3 dB/step analog display which can be calibrated logarithmically and is suitable for log measurements as logarithmic bar graph driver.

- About LM386:
LM386 is an integrated circuit containing a low-voltage audio power amplifier.It is suitable for battery-powered devices such as radios, guitar amplifiers, and hobby electronics projects. It can output 0.25 to 1 watts of power and has an impedance of 8Ω

- About 4mm LED:
It is a LED with a diameter of 4 mm, an unusual size. I found this LED on an old board taken from trash. I haven't found any others on the market.. don't worry, you can use a 3 mm LED!

- About Microphone Connector:
The microphone connection pad on this PCB was designed by me to allow the connection of different types of microphone capsules. Just be very careful in respecting the polarity + and - of the microphone.

► PROS and CONS of use a Vu-Meter with mic instead a standard one:
🟢 PROS: Portability, Not physically connected to the Amp, So cool!
🔴 CONS: Less accurate measurement than cable

For any other questions ask me in the video comments:)
✅ Subscribe to my YouTube channel It's FREE!

Chapters:
0:00 - Intro
0:34 - Circuit Explanation
2:03 - JLCPCB Factory
2:25 - PCB Upload
3:05 - Unboxing
3:40 - Start PCB Assembly
6:45 - Assembly Completed
7:00 - Music Test
7:50 - Circuit Diagram
7:55 - END

■▬▬▬▬▬ LINK & Support ▬▬▬▬▬■

Watch another video =)

WARNING: This video is only for demonstration. I don't take any responsibility.

Test Music: Elektronomia - Sky High [NCS Release]

#LM3915 #diyprojects #VuMeter

[ramybrahim]

thank you from Morocco .
I tried to do it several times without result, but, thanks to your diagram and component values, it, works very well .

[borsi]

Hello Stefano! Thank you for this fine circuit👍🏼Wish you all the best. Boris 🇨🇭

[sergioa]

Great project! Are you selling the finished circuit? Im interested. Thanks!

[UberWagen]

Not sure I understand the pot on the op amp. It adjusts the "sensitivity". But how do you go about calibrating it to be accurate?

[jamesrudacille]

Stefano!, awesome work! I copied it and it works. But, I would like to have a stronger signal from the mic. LM 386 is a power amp or preamp? What would I have to add or change in order to gain sensitivity in the mic. For example, I have to put the mic directly to my mouth or directly to a speaker to get the meter to move. Please advise. Thank you so much for your dedicated work. James

[charlie]

TPA3110 15w+15W Digital Stereo Audio Power Amplifier Board'
My question would be, is it possible to tie a vu meter to all Ic-powered mini amplifiers (power stages) loudspeakers? The TPA 311O doesn't go but TDA 2O5O goes nicely. The TPA 15w and an led secular are the last red. Where is the fault I ask respectfully?

[charlie]

My Honor, Sir,
I did a vu meter after a video you posted. Tied to the speaker, he goes with a succulent. My problem would be that the vu meter is at a maximum for a small volume. The signal to the vu meters should be reduced. The amplifier is 8w (small). Is it ok to put a poteciometer in or not because of impedance? And how erratic should be kilo ohm. Thank you very much I would be very honored.

[luigimorelli]

Che bello vederti tornare online... ma quanti PCB hai comprato?!?!? :-D
Ci sto lavorando anch'io, ne vedremo delle belle... ;-)
Domanda: il condensatore ceramico è da 47nF o da 470? La sigla 471 fa pensare alla seconda, mentre la lista componenti alla prima.

[kristianaudrigabriel]

What changes in the circuit diagram do I need if I want to power it with 5V power supply?

[therealnattylion]

Hello, do you think I could easily exchange the Mic with some wires to connect the whole circuit to a Arduino Board and use your VU-Meter circuit for a MIDI-Controller?

[francescoferoldi]

Salve, ho provato a fare ordine su jlcpcb ma mi ha dato errore, sono giusti i file gerber..saluti e grazie

[gulag]

Hello Stefano!
Please make a real-time digital clock circuit 89S52 RTC DS1307, I hope you will do it as soon as possible
Thanks you

[MiguelPámanes-ys]

Una duda. Un trimmer es lo mismo que un potenciometro?

[deanharrysmith]

Hi, do you know where to get the LM3915 from, all my sources in UK don't stock this IC
thanjks

[sebsbatako]

¿Dónde estaba cuando lo necesitaba como proyecto de la preparatoria? 😞😞
Pero bueno, a ver si lo puedo hacer después.
Por cierto, muy bueno. 😌

[leddanushka]

LED 40 wireless vu meter sarcut digrame, ,,, 🙏

[vaibhavk]

Led chasers and vu meter are
Meaning less projects pls share some useful projects in daily life

[afrasmiras]

What cause you study this knowledge?
Plz reply....

[마이클-jn]

I have a question!
1.Why did you use the diode ?
2.When I made the circuit, It was changed the Level after 100uF Capacitor. Before the Diode.

[charlie]

Super and super! Dear friend,
I'd say so, my friend, but I don't have the right.
I like to help you because I've been suffering for a year and I couldn't make the audio signal bigger.
I need a drawing with, say, two or three transistors (preamplifier for simple vu meter). I write with a fordito, and I tell you what I know, so how do you understand me? I bought everything from the net, ready but it didn't work. The vu meter is the simple LM 3915, 1k ohm resistor and that's it! The microphone electret, condensator .1 transistor. The signal is so good. Megyen but the volume should be weak or high. Help me if you can with a simple solution, I'm starting. BC 547.2N2222.2N39O4.