Listen to a Led Tea Light




Introduction: Listen to a Led Tea Light

Holiday Season is coming. Christmas decorations are everywhere. One of the gadgets that can be found everywhere are led tea light candles that really flicker. They are cheap, clean and not as dangerous as real candles.

But how do they work?

I read somewhere that the flickering was obtained by a sound generating chip hidden inside. I tried and tried to find the original article back, but I did not succeed. So I went shopping and made this instructable. This is not my invention and all credits should go to the person who first couldn't control his curiousity, just like me...

Important: I am not responsable if your experiments go wrong and you ruin your equipment, your Christmas or both. So be careful...

Step 1: Gather Materials

What you'll need is:

1) battery operated led tea light (less than 1 euro)

2) either one of following items:

- (computer) speaker
- mp3 player headphones
- audio cable

3) optional: little pieces of metal wire or a soldering iron in order to make the connections

Step 2: Open the Tea Light

In my case I had to do the following:
Remove the battery compartment cover.
With a small screwdriver open the bottom of the tea light.
Gently remove the electronics, it will be necessary to pull out the led from the silicone 'flame'. You'll see the led attached to a printed circuit board (PCB) and the PCB attached to the switch and the batteries.

Step 3: Connect to a Speaker

Connect the two leads from the led to the leads from a speaker. Be careful not to make a short circuit. If you want, you can remove the led and solder the wires directly to the PCB.

I don't think polarity is an issue in this case, so you can connect the two cables either way.

Now comes the moment of truth: switch on the tea light (at least the remains of it) and listen...

Step 4: Alternatives

1) Connect to mp3 player headphones

Connect the leads from the led to your headphones.
If you do not want to damage your headphones by cutting the cable, attach wires to the jack. Use the connections 3 (ground) and either connection 1 (right) or 2 (left). I found it more convenient to use connection 1 because of the little notch avoiding the cable to slip off.

2) Connect to your computer, amplifier etc.

Use an audio cable to hook up the tea light to a computer or amplifier. Connect to the line-in plug. I recorded the sound with my computer using audacity.

If you tried this instructable, led me know what sounds you found and enjoy the warmth of the tea lights or their music!



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    60 Discussions

    cool, i tried it. i took those obnoxious impossible-to-solder wires off of a speaker from some old busted headphones, and used that. also tried with a headphone jack, and recorded the sound with audacity. found out that the sound (at least the one coming out of my candle) is made up of a square sine waves... after a quick wikipedia search, i found out that square waves are often found in electronics and whatnot, and are used as timing references (clock signals). heres the sound:

    4 replies

    Yep - that's the noise my amp makes though higher pitched.I connected it across the power switch just to be an ON indicator and it feeds back into the amp as a quiet tinny dot dot dash dot. See my comment above.

    you know square waves and sine waves are different, right? corret me if i'm wrong.

    oh indeed, i know this. it's been a while since i posted that, but i imagine i said "square sine wave" to make it easier for the average reader to visualize what i was saying, without having to go look it up.


    1 year ago

    In the wayback when I wasn't much good at electronics - not that I'm much better now! - I used a self flickering LED from a similar tealight (but without the PCB) as the power on LED for a bench amp built out of an LM386 and an old speaker. And of course it made noise, a sort of ticking Morse code thing in the background. Not very loud so I could still use the amp for testing but it makes me smile every time I switch it on.

    Might be fun to revisit some of these self flickering LED's to see what type of noise toy one could make.

    This is awesome! I had no idea until I read about it in another instructable that links to this one. I used alligator clips attached to the plug of a little battery-powered speaker set (external speakers meant for mp3 players and the like). I did not recognize the tune, but it definitely was music!

    Speaking of curiousity, I once put a data CD into my CD player in hope of getting some weird fax-machine-type sounds (no, it did not work, unfortunately). I have to say that if I had found this on my own (with a light microphone, say), I would have been surprised enough to doubt my perception. ;-)

    Now I'm going to try it again with earphones and see if I can recognize the tune.

    This great! I plan on using it as a classroom demonstration.

    Ah,sweet sound of world's most abused song.
    Since the melody chip uses pitch of square wave(aka Pulse),it makes LED to rapidly turn on and off,making it look like it's flickering.
    Add 1uF capacitor between leads and watch what happens to the LED.

    The tea light plays Fur Elise, awesome!!

    does the tea light "dance to the music or not. if not how do i make it so it does. it will be great if i hook it up on like 20 other lights!

    i'm sure you could buy a tv-b-gone and wire it up like that, record the sound it plays then make a transmitter thingy, like an infra red led wired up to an audio jack, then put the sound on your mp3 player and use it as a tv b gone, or would it just not work?

    5 replies

    check this out! It tells you how to do just that! I'll make an instructable on it without a pocket pc or the adapter. (once i learn how to solder!)

    the best thing to do would be to buy one of those record your own message cards and record the sound onto that and then replace the other speaker with an IR LED

    i just tried but it doesn't work ir leds work at around 1 to 3 volts and sound works at around.5 to 1 volt you will need to somehow amplify the sound

    thats a interesting concept. i am a bit skeptical but im sure you could try it. you never know until you do.

    I got some random piece that I can't identify; it sounds like a Ukrainian folksong if I had to guess. I've got another model of led tealight at home that I'll check out later too.

    1 reply