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Electronics Multichannel version of cpemma's PWM MkII, LED throbber, audio controlled LEDs

Discussion in 'Modding' started by Emon, 7 Oct 2006.

  1. Emon

    Emon What's a Dremel?

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    *Long post! I apologize, but bear with me, I promise it has nice grammar and is easy to understand!*

    I have a project where I have red, green and blue decorative lighting that I want to control with one of three methods. Controlled by sound (with help from this thread), manual brightness control with cpemma's PWM MkII, and adjustable LED fading or throbbing.

    The audio control is easy. I just need a three channel version of theshadow27's controller, using low-, band- and high-pass filters for each component of the lighting. No problem.

    I could also just assemble three MkII PWM controllers, but that seems cumbersome, especially when cpemma talks about a multi-channel controller near the bottom of the page. I'm not sure if he means a multi-channel controller where each channel gets individual control, or simply driving more channels. He seems a little vague and I'm not sure where to proceed.

    And as for the throbbing, I'll probably just build three of those circuits. The trouble is that I'd like to adjust the rate at which the lights throb. Perhaps anything from a slow in and out fade to a quick throbbing. There are two pots for adjustment, but I'm not sure quite sure which would control the rate...I'm a little confused by cpemma's wording on what those parts do. I started to build one to just test it myself, but I fried the only LM358 I had when I wired the pins up incorrectly. :wallbash: I plan on using only three external pots for each adjustable mode. That means the pots need to be wired into both circuits. That could be a problem since the adjustment pots don't really match. But ah, I can do a little potentiometer surgery and make a hybrid dual pot that has one channel of appropriate resistance for each controller. What I'm trying to find out from you guys, is which pot in the throbber circuit is the one I want to adjust the throbbing rate, and what value I should use to get the greatest range of adjustment. I would figure it out myself but I'm ordering parts, and all the pots I have on hand are too good to go hacking up! That and I don't have a working LM358. :blush:

    So yeah, in this project, I have three lighting modes for controlling R, G and B components. Not all at once, of course. I'm probably just going to use a simple rotary switch to shunt the voltage to the appropriate controllers. I'm making an order from Futurlec for various parts and was going to pick up one of these. They're all marked as MBB, make before break. I assume that means that a connection with the new contact is made before the connection with the old one is broken. I'm pretty sure having a short moment when all three controllers are supplying voltage to the LED isn't going to be a problem, but I wanted to check with you guys.

    Thanks for bearing with me thus far through my long post. Thanks for any help.

    Cheers!
    Matt
     
  2. cpemma

    cpemma Ecky thump

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    Vague? See my sig.

    It's a multichannel fan controller, like them what you can buy, a speed knob for each fan channel. A PWM power controller compares a variable DC reference voltage (from a pot or thermistor-resistor potential divider) with the fixed highish frequency wave signal to vary the mark-space ratio of the power supply. The basic LED throbber is an adjustable low-frequency wave that turns the LED supply up and down at that frequency.

    You can save some parts (mainly pots) by making a PWM throbber, where there's just one fixed high-frequency wave oscillator for everything and a variable speed low-frequency wave oscillator providing a reference voltage for each LED channel. Uses more opamps, but they're cheap.
     
  3. Emon

    Emon What's a Dremel?

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    :rolleyes: Why do I even bother with this place anymore? I can understand if you can't be bothered to write very detailed descriptions of every project, especially after all the work you have done for the community, but don't insult my intelligence.

    Edit: I'd like to apologize for the above. cpemma did try to help, I guess I had a stick up my ass at the time.
     
    Last edited: 8 Oct 2006

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