I love lights, and I love music… Naturally a color organ is something that I always wanted to make. However the circuits are often pretty complicated, using many op amps, etc. I'm sure that many people feel the same way.
Now the wait is over. If you are a bit familiar with electronics, you can build a 3 way color organ with only 29 components. I've streamlined the circuit to the absolute minimum, using easy to obtain, inexpensive parts. In fact, if you are electronic hobbyist, you probably have all the parts sitting around already!
In case you've never heard of a color organ, it's a device that emits different colors of light based on sound. LED Color Organ Triple Deluxe divides sound into three frequency bands, and emits red, green and blue lights accordingly.
Watch the video and you'll see what it does.
Step 1: Overview
Three groups of LEDs each responds to high, mid, and low frequencies of sound.
In order to simplify the circuit, I design the Organ to connect to a headphone output of audio equipment. The power source can be a 9V battery, or a regulated AC adapter that outputs 9 V. (Most wall wort type adapters output much higher voltage than they are rated, therefore not suited.)
I'd like to thank Collin Cunningham of MAKE: Magazine for publishing his LED Color Organ. His version is a lot more sophisticated and complex (read: expensive), which led me to design a super simple version.
Step 2: Parts
Here's the BOM (Bill Of Material):
- 3x 100 ohm resistors
- 1x 180 ohm resistors
- 1x 270 ohm resistors
- 2x 1k ohm resistors
- 4x 2.2k ohm resistors
- 2x 10k ohm resistors
- 1x 0.047 uF capacitor
- 1x 0.01 uF capacitor
- 1x 0.47 uF capacitor
- 1x 1 uF capacitor
- 1x 10 uF capacitor
- 1x 1N4148 diode
- 1x 2N2222A, 2N3904 or equivalent NPN transistor
- 3x 2N2907A, 2N3906 or equivalent PNP transistor
- 6x LED (2x Red, 2x Green, 2x Blue recommended)
All capacitors can pretty much be of any type as well. Just make sure that the voltage is rated at least 16V. However it's safer to stick to film type for smaller value ones, and aluminum electrolytic type for larger value ones. Those are the most common types anyway.
The diode can also be most any silicon diode. I'm using a switching diode 1N4148, which is the most widely available and probably the cheapest.
The transistors can also be pretty much anything. The NPN one here is a bit picky, as it deals with the audio signal (hfe needs to be reasonably high). Compatible transistors include: 2N4400, 2N4401, PN3646, MPSA06 for NPN. For PNP: 2N5401, MPSA55, MPSA56.
The LEDs can be of any color, however the resistor values are adjusted for the colors used here. If you use different colors, use 270 ohm for red, because red LED have lower forward voltage, thus need larger resistor to limit the current. The current limiting resistors for the LEDs are adjusted to achieve brightness balance between them. So your mileage might vary.
Step 3: Construction & Circuit
I designed the custom PCB for this, however it's not ready for a couple of weeks. The board dimension is 1.8 x 1 inch. Please let me know if you are interested in purchasing the PCBs.
For those who want to make their own PCBs, you can download the Gerber files. (Please note that this PCB design has not been tested yet.)
Connection to the audio equipment (aka iPod) is via a disassembled stereo headphone cord. You will usually find three conductors in those cords - two of them carry the audio signal, and the shield/braid is the ground connection. I soldered a 3 pin header to make the connection to the breadboard easier.
A bit about the circuit
The basic idea behind the Color Organ Triple Deluxe is the same as many other circuits before it. Most color organ circuits divide audio signal into three frequency bands, and drive light sources acoording to the signal levels. My circuit combines the filter stage with the light drivers, saving a lot of parts. I won't claim that it does the same thing as more sophisticated circuits do, however it works pretty well.
Step 4: Triple Deluxe and Beyond
Once you put this color organ in a nice little case, you can take this mini light show with you anywhere. Great for outdoor activities!
It's so simple & cheap to make, you've got to try it!
You can add a few more parts and your ingenuity to take this project further.
You can use a bit higher voltage and drive 3 LEDs in series (9 total). Or use opto-isolators to control room lighting. I think this circuit can also be used as a pre-processor to feed audio signal into Arduino or other microcontrollers to create sound activated gadgets. (Use 5V power supply if you want to interface with Arduino. You can replace the LEDs with 1k ohm resistors and take the signals from the collectors of Q2 - Q4. The voltage level is low when there's no sound.)