Dimmable LED project

Discussion in 'The Projects Forum' started by altontoth, May 8, 2009.

  1. altontoth

    Thread Starter New Member

    Apr 11, 2009
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    Looking at using a ucontroller to control LED's for dimming / mood lighting. The idea would be that on the main unit, there would be a small LCD display that with a number of buttons, one could change between each of 4 colours to control, and then use a couple more buttons to adjust the brightness levels up and down. That part is easy enough to get working with the ucontroller. However, the idea is that these LED's are in clusters (50 clusters of 4 LEDs, one of each colour), that are all chained together. Each colour would be operated as a single channel.

    My question is this. Instead of having to run wires for each colour out to all the clusters (GND, RED, BLUE, GREEN, WHITE), is there a single chip that can decode a single wire signal and change brightness levels on 4 channels (+5V, SIGNAL, GND)? I'm not even sure of what I should be searching for to find hints on what I want.

    Sorry if I confused anyone.

    Alton
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    How far apart are these clusters? This sounds like a microcontroller project to me.
     
  3. altontoth

    Thread Starter New Member

    Apr 11, 2009
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    Clusters would be 2-3' apart strung up around the ceiling of a room. The idea is to use a microcontroller as the main processing unit, but trying to limit wire count around the room.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    I was thinking in terms of each cluster having it's own microcontroller. That is the only way you're going to eliminate the wires you're wanting to get rid of. You will still have power (2 wires) and signal, though it is possible to incorporate the signal into the power wires.

    The other possibility is to buy a cable that has all the wires within it, so from the outside it appears as one wire. Exactly what you are not wanting to do. With this approach you could create a "net" approach, which could actually be attractive if done right.

    Reason I mention the latter is you will have to have some wires reguardless, for the power wires. Unless you are planning on using batteries.
     
  5. altontoth

    Thread Starter New Member

    Apr 11, 2009
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    No I realize that. My hope was that someone out there had seen a non- microcontroller IC that can be used to control multiple LEDs' brightness. I am willing to shell out for a single one, but not necessarily for 51, even if the other 50 are ATtinys or something. I guesse only solution for varying brightness with a microcontroller would be PWM through a set of Mosfets, hey? (one for each colour). 5 wire cable running to each cluster.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    Unless you are using a special LED (expensive that) that requires 300ma or more, there are plenty of conventional chips that will do it, such as a CMOS 555. They can be had in quantity for less than 50¢ each.

    I don't think you're going to find a ready made chip, but this is a simple project overall. The cost of LEDs is what's going to hurt.

    I'd come up with a prototype (controller and 2 modules) on paper and work from there.

    Have you read this?

    LEDs, 555s, Flashers, and Light Chasers
     
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