LED Project Need Help

Discussion in 'The Projects Forum' started by CBux, Mar 2, 2015.

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  1. CBux

    Thread Starter New Member

    Mar 2, 2015
    Hey Everyone,

    I am working on a project for a customer subwoofer box for a friends car and I want to make sure I am covering all of my bases because I have never had a request like this before so I want to make sure it works. I have done a bit of research but I feel like I am still missing something.

    The project is to have the subwoofer box lined with LED strips and power those lights from the single going to the subwoofer from the amp.

    I plan on using standard 12volt LED strips, TIP31 Transistor, Switch (Two or Three terminal?), and 18 gauge automotive wire. I will connect the transistor to the positive and negative going into the subwoofer and then wire the leads from the transistor to a switch so that it can be controlled when the lights are to sync with the music or when they are to be off.

    My questions are:
    1. Do I need a resistor somewhere in the circuity to prevent the LED strips from blowing?
    2. How should I wire it to the switch to get the ideal effect? (2 terminal switch that is just an interruption for the power wire leading to the LEDs or a 3 terminal that is wired with the negative coming from the transistor?)
    3. Am I missing anything else?

    Here is a picture I found that kind of illustrates the circuitry I had in mind but does not include the switch. Also note that I will be using 18G wire instead of a 3.5mm jack.
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    A common strip rated for 12 V DC has 3 LEDs & a resistor in series, repeated in parallel for the strip lengt.
    As automotive was mentioned, thi post might be closed.
  3. CBux

    Thread Starter New Member

    Mar 2, 2015
    So I dont need a resistor then. How about the switch?
  4. wayneh


    Sep 9, 2010
    I think what you mean is not to power the LEDs from the signal, but to switch them by the signal, right?

    Your LED strip is likely designed for full 12V (automotive, actually ~15V) operation and as such should not need an additional resistor. But you should inspect and research until you are certain.

    Your circuit is more-or-less the right idea, a small signal on the base controls the larger current through the LEDs. But I'm not sure it will give you the effect you want. Do you want the light on most of the time, flashing intermittently, or what? Also, I think you want a resistor on the base of the transistor to reduce its load on the subwoofer amp.
  5. bertus


    Apr 5, 2008

    I am closing this thread as it violates AAC policy and/or safety issues.

    6. Restricted topics.

    The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

    • Any kind of over-unity devices and systems
    • Automotive modifications
    • Devices designed to electrocute or shock another person
    • LEDs to mains
    • Phone jammers
    • Rail guns and high-energy projectile devices
    • Transformer-less power supplies
    This comes from our Tos:
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    There will be enough sites where automotive questions can be discussed :
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