What is a Music Reactive LED?
Music reactive LED circuits are simple electronic circuits that respond to the varying sound and beats generated by a nearby source of music. Music reactive LEDs are generally used for advertisement purposes. Since these LEDs have a tendency of catching the attention of the audience. They are also used in sophisticated VU meters and sound equalizers, in order to serve as an indication for varying music levels during production and recording. So, in today’s tutorial, we are going to go over a step by step process on How To Make a Music Reactive LED Circuit Using NPN Transistors.
No matter what configuration is used to make a music reactive LED, the working principle remains mostly the same. An audio input from a PC or smartphone is taken as the input. This input is then cleaned to remove any noise and is then passed through a series of switching transistors. The LEDs connected at the output of the circuit then mimic the switching frequency of the transistors. Hence, appearing to imitate the synths and beats of the melody.
Hardware Component
You will need the following parts to build this project.
| S.No | Component | Value | Qty |
|---|---|---|---|
| 1) | Electret Mic | 5mm | 1 |
| 2) | Transistor | 2n2222A, NPN | 2 |
| 3) | LED | 5mm, 3.5V | 4 |
| 4) | Capacitor | 100nF | 1 |
| 5) | Resistor | 10K, 1M | 3 |
| 6) | Soldering Iron | 45W – 65W | 1 |
| 7) | Soldering Wire with Flux | – | 1 |
| 8) | DC Battery | 9V | 1 |
| 9) | Battery Clips | – | 1 |
| 10) | Veroboard | – | 1 |
| 11) | Jumper Wires | – | As per need |
Useful Steps
1) Solder the first 2n2222A transistor on the veroboard.
2) After that, solder a 100nF capacitor with the base terminal of the BC547 transistor.
3) After that, solder a 1MOhm resistor between the 100nF and the BC547 base juntion.
4) After that, solder a 10K resistor with the 100nF capacitor. Also, solder another 10K resistor with the collector terminal of the first BC547 transistor.
5) Now, Solder the second BC547 transistor on the veroboard. Solder the base terminal of the said transistor with the collector pin of the transistor. Also solder the emitter pins of the two transistors together and connect them with the GND of the circuit.
6) After that, short all the +ve and -ve pins of the LEDs with the same polarity. after that, solder the -ve pins of the LEDs with collector terminal of the second tranistor and the +ve pin with Vcc of the circuit.
7) Solder the +ve pin of the electret mic with the 100nF capacitor and the -ve pin with the GND of the circuit.
8) Connect the -ve pin of the battery clip with the GND of the circuit and the +ve pin with the resistor and LEDs.
9) Power up and test the circuit.
Working Explanation
The working of this circuit is actually pretty simple. Audio input from a device such as a smartphone is taken as the input by an electret mic. The microphone transduces the sound waves into an electrical signal to be used by the circuit. The electrical signal then passes through a coupling capacitor (100nF). The coupling capacitor blocks the DC component of the input audio signal, allowing only AC to pass through.
The output from the capacitor acts as a control signal on the base of the BC547 transistor. The collector output from this transistor is then fed to the base terminal of the second BC547 transistor. The amplified collector output from the transistor triggers the LEDs to glow. You can use a 9V battery to operate this circuit.
Applications
- Usually used in devices such as VU meters to facilitate the process of live music production and recording.
- Also used in fancy advertisement banners used in night clubs.
See Also: How To Use DHT11 Humidity & Temperature Sensor With Arduino Uno | ±12V Dual Polarity PSU Using LM7812 And LM7912 Voltage Regulator IC | How To Make A Heart Rate Monitor Using LM358 IC | Heart Beat sensor
