Synchronizing-Music-to-a-LED

The project shows how to synchronize music to a LED, designing and building a low-power audio amplifier/speaker driver based on a LM386N, a LM358 low-power dual Op-Amp, and a 2N3904 NPN Bipolar Junction Transistor.
The LM386 is a low power amplifier. Its default voltage gain is 20, which can be vary by placing an RC circuit between pins 8 and 1. Its gain can be vary to any value between 20 and 200. LM386 is biased by an external DC power source so it provides power to the AC signal and hence enhance the AC signal. That why its output signal is greater than its input signal. The voltage rating of power supply must be between 4 – 12 volts and current rating greater than 100mA for its proper working. We can control the gain and also remove the noise from the signal. It can be used in ultrasonic drivers, portable audio players, in TV sound systems, servo drivers, line drivers, in radio amplifiers, especially in AM and FM, and power converter. Building a summing amplifier around the LM358, we are combining several inputs into a common output signal and bringing clearness to the sound. Audio speakers convert electrical signals into mechanical motion. The electric signal is passed through a coil of wire (the “voice” coil), which is suspended a strong magnetic field provided by a permanent magnet. A time-varying current in the coil leads to a mechanical deflection relative to the magnet.
Placing the 2N3904 we are amplifying the power as well, since is a general-purpose transistor, and act as another filter to bring clearness to the sound. At the output a LED is placed with a 6ohms resistance, in order to synchronize the tone frequency with light. For sound input an Arduino Uno is used generating a melody at different frequencies to create the flash in the output LED. For programming this Arduino, a MATLAB application is used with the code attached.