LED Backlight TV Trigger




Introduction: LED Backlight TV Trigger

About: Why pay for stuff when you can make, build, hack, macgyver it. They are better and cheaper 100% DIY.

Having a light on the back side of the tv brings a lot of advantages, diminish the fatigue on the eyes when flipping channels and also when transition between dark and bright scenes, this two sceneries present itself when the only source of light is the tv screen.

You can experiment this with a simple flashlight on the back of the tv, you will see that seeing tv becomes more comfortable in a dark room.

There are a lot of solution on the market of light to place on the tv but they require a separate remote control to trigger, on this project i will show you how to use a normal the tv usb connection to trigger the LED light.

Step 1: Watch the Video

Watch the video and see how the project works.

Step 2: Gather the Material

You will need for this project:

- A 12V 800ma Power Brick

- Led Strip

- Enclosure Box For Electronics

- USB Cable

- Circuit Board Perforated

- LM338

- 4N25

- 12V Relay

- 1N4148

- BC548

- 120 Ohms Resistor

- 330 Ohms Resistor

- 1K Ohms Resistor

- 5K Ohms Potentiometer

- 0.1uf Capacitor

- 1uf Capacitor

Step 3: Get Started

Follow the circuit diagram and solder the components on the board.

I used a strip with 30 LED's and place two strips one on both sides of the TV but you can place more for a bigger effect.

This LED strips are easy to place because they have plastic bracket that glues on the TV.

Step 4: How It Works

When the TV is turn on it gives 5V out by the USB connection triggering the 4N25 turning on the lights.

The LM338 allows you to dim the lights at your taste by the 5k potentiometer.

There is a small delay on the output of the 5v by the TV when it turns on and off but it's not a big deal.

Step 5: Final Thoughts

This simple project makes it easy turning on and off the LED Backlight and diminish the fatigue on the eyes because the iris was always a light to see avoiding to have to adjust every time between the changing scenes.

Tell me on the comments below what applications you will use this for.

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    5 Discussions


    5 years ago on Introduction

    I used dusk till dawn activated led night lights pluged into cheap seperate exstention cords. Works like a charm! In my bedroom I plugged them into a multiple plug outlet then plugged the multiple plug outlet into a wireless transmitter, and then plugged that into a power strip! I put the wireless light switch on the back of my headboard. So I could turn off the night lights off from my bed after I am done watching t.v! The t.v. In the living room just stays back lit all night long!


    5 years ago

    Sounds overly complex to me. I would used a BC547B to trigger the 12v from the 5v from the USB port, and a 555 to vary the brightness


    5 years ago

    Hi ya. Where have you used the bc548? I don't see it on the drawing.

    Engineer of None
    Engineer of None

    Reply 5 years ago on Introduction

    Hi, sorry didn't write that, is the transistor connected to 1k resistor.