Designs for LED Color Organ+Plasma Speaker

Discussion in 'The Projects Forum' started by Doctor Hufflepuff, Feb 28, 2016.

  1. Doctor Hufflepuff

    Thread Starter New Member

    Feb 28, 2016
    For a project I am creating a plasma speaker complete with lights (specifically RBG LEDs) which are supposed to flash with the music. I am using a plamsa speaker found online ( and I am modifying a color organ (

    To make this project unique, I plan to utilize the multi-color ability of the LEDs to have two main settings: one for customizing preferred color for each of the three music frequencies (for example, setting the LEDs for low frequency to red, medium to purple, and high to blue, or any other combination), and the other for using the proportions of low, medium, and high frequencies to select the proportion of red, blue, and green in each LED, effectively playing a different color for each sound.

    To do this I have developed the following circuit, which is essentially the color organ circuit connected to an array of voltage dividers. My question: can anyone who has experience/knowledge of how this circuit would behave tell me whether or not it will work, and does anyone have any suggestions on how to improve the design, preferably without increasing the price of components?

    Notes: The switch I plan to use to alternate between modes is in the top right corner of the picture. I do not know if I need to add resistors between the switch and the 2n222 transistors I am using as electronic switches to direct the flow of power. If anyone knows, please teach me HOW to find the resistor values, as I am using this project for a learning experience as much as a fun way to pass the time.

    If I left anything out please just ask. Thank you to anyone who can offer any help/input. Thanks

  2. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    This is better than the schematic on the other forum, but you still have an isolation problem with the way the anodes of the LEDs are connected together. "All Red Anodes" connecting to R15 also connects together R14, R17, and R20.

    Driving DC loads with multiple sources usually requires isolation diodes to keep things from cross-connection incorrectly.

  3. Doctor Hufflepuff

    Thread Starter New Member

    Feb 28, 2016
    So, could this problem be solved simply by placing a diode at the end of each voltage souce, before the LED?
    Also, does using the 2n222s prevent the voltage output problem as opposed to the TIP31s?
    Thanks for the quick help!