# Backlit 1/4" Audio Jacks

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## Introduction: Backlit 1/4" Audio Jacks

Add an extra touch to your audio projects by backlighting the 1/4" audio jacks with LEDs.

Here are the parts you'll need:

1/4" stereo jack Radioshack 274-141 or Radioshack 274-312
LED, I used Radioshack 276-017
1/4 watt current limiting resistor- you'll calculate the correct value for your LED
22 gauge stranded wire
solder
hot glue
electrical tape

Prepare the Jack:

My jack came with a plastic casing, I removed this to expose the three leads of the jack (this is a stereo jack so the three leads are for left channel, right channel, and ground, a mono jack will only have two leads).  Solder a green wire to each of the signal leads of the jack (fig 4).  The larger lead is the ground lead (fig 5), I'll solder the LED directly to this pin once I've soldered a current limiting resistor to it.

Prepare the LED:

I used a 5V supply to power my LED.
I calculated the value of the current limiting resistor from the following information:

LED forward current: 25mA
LED forward supply: 3.3V

voltage across the current limiting resistor = 5V - 3.3V = 1.7V
V = I*R
R = V/I
R = 1.7V/0.025A
R = 68Ohms

Remember, this is an absolute minimum value for the current limiting resistor, you should always add a little extra resistance to ensure that you are not running your LED at its maximum ratings.  For these LEDs, I used a 100ohm resistor instead of a 68ohm.  Don't worry about using too large of a resistor, worst case scenario your LED will just glow dimmer, you will not break them.  If you are not sure about the ratings of your LED, use a 220ohm resistor.

Solder the resistor to the anode (long lead) of the LED.  Solder a red wire to the other side of the resistor.  Cover the whole lead with shrink wrap so that it is completely insulated (fig 7).

Attach the LED:

Solder the cathode of the LED to the ground pin of the jack so that the LED is pointing into the jack.  Make sure to leave enough room for the male end of the cable to fit inside the jack.  Solder a black wire to this junction. I like to use some hot glue to keep everything insulated and supported in the jack and then cover the whole thing with electrical tape.  Connect the red wire to 5v, the black wire to ground, and the green wires to your signal.

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## 10 Discussions

@amandaghassaei; Hi! I have two questions - does the LED block the jack opening when you're trying to put the plug in? And does putting the LED and resister inline with the ground affect the sound? I agree it looks awesome. Cheers! : ) Site

thanks! yes, when you install the LED you have to make sure that it will not block the plug. Plug a cable into the to the jack before you solder the LED down and you should have no problem. No, it won't affect the sound, the circuit for the LED shares a common ground with the signal, that's it, it does not put any kind of load on the signal.

This could be a useful and easy project for USB ports on a computer. As long as they are open on the backside like some that I've seen. I have 2 ports on the front of my tower that are all the way down by the bottom. I'm always fumbling to get a cable plugged in because you can't see them directly unless you get down on hands and knees.

I really like this. A project i've had in my mind for a while is to add an mp3 input jack to my car stereo for family road trips. having a lit plug will be pretty useful when driving at night.

nice job!

For that project, you could use the instrument cluster lighting as a power supply, that way it would only be lit when your parking / headlights are on. Just make sure to recalculate the value of the resistor to take into account the +12v supply.

If only they would do this with the charge and headphone jacks on cellphones!

You can use a jack with a cut-off switch to turn on and off the LED.

Awesome idea! I love it when that extra bit of pizazz is so easy to achieve.

Great little idea!! Looks really nice. Gonna have to use this in a project at some point.