Introduction: LED Organ Circuit

This Instructable flashes lights along with music. There are two red, two green, and two yellow LED's. The red LED's blink along with the music at a high frequency. The green LED's flash at a lower frequency along with the music while the yellow LED's flash at the lowest frequency along with the music. The input and output are connected to the circuit so the music can play through the speakers as well as the lights flashing along with the music.

Step 1: Parts List


-audio jack/ 1

-10uF capacitor/ 1

-green LED/ 4

-red LED/ 4

-yellow LED / 4

-2n3904 transistor/ 1

-2n3906 transistor/ 3

-9v battery/ 1

-1uF capacitor/ 1

-.47uF capacitor/ 1

-1n4148 diode/ 1

-100 ohm resistor/ 3

-10k ohm resistor/ 2

-180 ohm resistor/ 1

-1k ohm resistor / 2

-2.2 ohm resistor / 4

-270 ohm resistor / 1

-.01uF capacitor / 1

Step 2: Background Knowledge of Filters

High frequency filter:- A high-pass filter (HPF) is an electronic filter that passes signals with a frequency higher than a certain cutoff frequency.

Medium frequency filter:-A medium-pass filter is just like a high pass filter, however it only allows medium frequencies to pass through the circuit.

Low frequency filter:- A low-pass filter (LPF) is a filter that passes signals with a frequency lower than a selected cutoff frequency

What are filters used in?

Filters are used mainly in speakers for equalization purposes. These filters make sure that each frequency is heard equally.

Step 3: Construct Circuit

1.) The first part of the circuit to construct are the beginning transistor and resistor for the audio input and output. This consists of 6 resistors, a capacitor, and a transistor.

2.) Next assemble the high pass filter with 2 red LED's, 2 resistors, a capacitor and transistor

3.) Now assemble the medium pass filter with 2 green LED's, slightly higher resistors, 1 transistor, and 2 capacitors.

4.) Next, assemble the low pass filter with 2 yellow LED's, even higher resistors, a transistor and smaller capacitor.

5.) Now connect your battery and audio input.

Below is a link to a video for step by step construction of the circuit:

Step 4: Additions

We decided to add an output aux port that you can plug into your speakers. This allows you to hear the music that is going through the circuit.To do this you simply need to add another aux port and connect it to the input aux.

How to connect the output:

1.) place the port on you bread board next to the input port.

2.) wire the left, right and ground legs of the output to the corresponding input legs

3.) make sure both the input and output of each leg runs to the respected resistors in the circuit

4.) Finally connect your phone for a music source to the input and a speaker to the output

Step 5:

[* this should probably be step 4: explain how to operate your circuit/device ]