Color Organ Page

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NOTE: an all new 8 channel color organ design is available. Check it out here.

A color organ is a device that splits music up into numerous frequency bands and modulates colored lights (typically one color of light per band) according to the musical content. I used to build them in my younger days for use when listening to music and for some of the bands I was in. Color organs were part of the "scene" in the 60's and 70's.

I designed this color organ from the ground up using digital technology instead of the more traditional analog technology typically used in color organs. After I got the color organ to work I wrote a series of three articles for Nuts and Volts magazine that discussed the technology and the implementation of the color organ. These articles appeared in the Sept 2007, Nov 2007 and Jan 2008 issues. Nuts and Volts magazine is available in the Pikes Peak area libraries. If you would like to read these articles they are available here.

September 2007	Floating Point Multiplication and Division without Hardware Support
November 2007	Lattice Wave Digital Filters
January 2008	Psychedelia II - A Digital Color Organ

Here are some fotos I did for the article which shows how the color organ was constructed.

	Here is the main color organ circuitry. The micro controller which runs the color organ is on the blue board at the left.
	The complete color organ was built onto the back panel of a triangular display box I bought at Hobby Lobby. The LEDs are the super bright variety that are bright enough to be seen easily in daylight.
	Here is the back of the finished color organ. Here you can see the control panel.
	Here is the front of the color organ. It turned out nicely I think.

The color organ has a micro controller (computer) for a brain. This chip is smaller than the nail on your little finger. I purchased a development kit for this little micro for $20 from Texas Instruments (www.ti.com). The complete development kit is built into a USB dongle which is amazing in itself. The photo below shows you the scale of what I am talking about. With the $20 development kit (which includes an assembler, linker, C compiler and debugger), TI has truely brought micro processor development to the masses. The micro controller target board is in the top left and the development kit is at the bottom.

Below are the schematics and parts list for building the color organ.

Parts List

Part Designation	Value	Notes
C1,C4,C5,C6,C8	4.7 uf capacitor
C2,C13,C15	0.1 uf capacitor
C3	230 pf capacitor
C7	0.022uf capacitor
C9	0.01 uf capacitor
C10	0.02 uf capacitor
C11	0.04 uf capacitor
C12,C14,C16	47 uf capacitor	polarized
R1	4.7 K resistor	¼ w 5%
R2,R6,R7,R8,R13,R14	1 K resistor	¼ w 5%
R3,R4,R9,R10	20 K resistor	¼ w 5%
R5	1 Meg trimmer	10 or 20 turns
R11,R12	1.6 K resistor	¼ w 5%
R15	270 ohm resistor	¼ w 5%
R16,R18,R20,R22	470 ohm resistor	¼ w 5%
R17	22 ohm resistor	1 w
R19	18 ohm	1 w
R21,R23	6.8 ohm	1 w
D1	1N5819 diode	Optional reverse voltage protection diode
D2,D33-D42	Superbrightleds.com Blue LED	RL5-B4630
D3-D12	Superbrightleds.com Red LED	RL5-R5015
D13-D22	Superbrightleds.com Yellow LED	RL5-Y5030
D23-D32	Superbright.com Green LED	RL5-G5023
J1	Stereo 3.5 mm / 1/8” jax	Line input connector
J2	2 wire power jax	Optional
J3/J4	Inter board connections	Optional
M1	Condenser microphone	Jameco #160979
Q1-Q4	2N4921 switching/power transistor	Heat sinks aren't necessary
SW1	SPDT	Mic/line switch
SW2	SPST	Power off/on switch
U2	LM2940CT	5 volt 1 amp voltage regulator
U3	LM3940IT	3.3 volt 1 amp voltage regulator
U4	MSP430-F2012	uC target board. Available from TI.com.
U1	LM324	Quad op amp
U5	74HCT139	2 to 4 demultiplexer
U6	74HCT04	Hex inverter/buffer

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