WARNING:
Using a Color Organ in your Vehicle, Especially While Driving is:
"Probably Illegal and Definately Distracting".
So If you do this, It is at your OWN RISK.
Back in the 1970's these were popular for use in homes and the colored bulbs were typically place in a box with a sheet of "rippled/bubbled" Plastic in front to break up the light patterns. Some units gave very impressive light patterns.
Using an LM324, this circuit has 4 Active BandPass filters for the Bass, Low Mid Range, High Mid Range and Treble frequencies. ** The use of All BandPass Filters give Much better seperation beween the various frequency.
Setting it up:
1) First Turn Up all the Filters to Full On. 2) With the Music Playing at Normal Volume, Turn the Master Level so All Lights are now on or just Flashing.
3) Than the 4 filter control are set "to equal out the Lights" so the lights all flash in about equil amounts of time. (So Reduce the Lights that are Full On, so all light blink about Equil.)
The Master control, (usually a regular potentiometer) is than used to set for various incoming volume levels. (I just used a trimpot on my proto for testing purposes.)
As Shown on the Schematic, Proper Rated FUSES are Highly Recommended. The Fuses protecting the Mosfets should be "Automotive Types", with a voltage rating of 32 Volts.
"T1" is for Isolation and signal boost. It can be almost any small audio transformer, used in reverse. The one stated here is reasonably priced and fits the board nicely. "T1" is Essential to "Isolate" the audio output from ground on Non-Grounded Audio Systems.
A Small Light bulb is placed in series with this Isolation Transformer. I Recommend a #1819 or 1821 (28 Volt) Minature light bulb in here. It will better compensate for Excessive current flow.
I have operated this circuit from a Headphone output, Quite low power. But I really recommend driving this from the Amplifiers Output.
Heatsinks May be required on the Mosfets, Depending on your load Currents. The Mosfets I supply are typically rated at 50 Amps or More. So With a Proper Heatsink, it is Probably suitable for loads up to 30 amps per channel. But it is UNLIKELY your Car can Handle that much Current.
The Loads: Although I Prefer Standard Filament Bulbs, You can also use Many LED's with there appropriate Series resistors. Or a considerable number of 12 Volt Incandescent Bulbs.
Filament Type Bulbs give a Much Better Effect than LED's, because they give a better Brightness Variation. The Tiny Series String Christmas Tree Bulbs Work Excellent. Typically they come in Various Colours, they are Cheap and are between 2 to 4 volts each. So you can Series, 3 to 6 of them, Than Parallel these to use Many Bulbs on each channel.
Other Devices such as the 12 volt Colored Neon lights may also work. I Don't have them to give it a try.
The PCB and parts are available for this 4 Channel Color Organ. Just Email Me for this Info.
4 Channel Color Organ Schematic for N-Mosfet
Possible LED Wiring Arrangements