Picture of musical beat thief
No we're not stealing musical beats of any kind but we are going to make leds flash to music using a joule thief circuit with a slight modifacation
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Step 1: Finding parts

Picture of finding parts
you could buy parts or salvage them like I did , but anyways you need :

toroid bead
3.5mm audio jack
thin wire
led (any colour)
270 ohms resistor (red,violet,brown,gold)
s9014 transistor or equivalent
stripboard (optional)

( ) datasheet for the transistor.

Step 2: Construction

Picture of construction
First off I would start with the toroid you need really thin wire with quite thin insulation, you want about 9-11 wraps around the toroid bead. After that you should solder two different wires from opposing ends together, so now you should have 3 wires coming out of the bead the two you just soldered are now the + in wires,now take one of the remaining wires and solder the resistor to it then solder the resistor to the middle pin of the transistor , take the last wire from the toroid and solder it to the collector of the transistor.

Solder the + leg of the led to the collector on the transistor and the - leg to the emitter.

Also add a length of wire to the - leg of the led for the ground wire.

Then solder the ground wire to the 3.5mm jack and the positive to the left or right channel.
jacob56805 years ago
 I think I blew up my transistor while soldering ( way to hot ) and the transistor is actually emitting sound... O_O I can hear the beats of my music from the transistor

frag_bomb (author)  jacob56805 years ago
you should deffiently put that on youtube =D
Fixed the problem by reversing the resistor and ground. :P
derbert5 years ago
(removed by author or community request)
derbert derbert5 years ago
i used a transistor that went red, violet, red, gold. does that matter?
frag_bomb (author)  derbert5 years ago
yes it does , at that resistance i dont think it will work but depends on your input i suppose
nice ible anyway...I've got a strip of 3 blue LEDs wired to my laptop subwoofer for some sweet ground effects everytime the bass kicks...I love it....I did this for my friend's car too...underdash lights that go with the beat. I LOVE LEDs _
hopefully not wired directly in after the amp because if it is it can make for bad sound quality or even damage your system
u cant wire it b4 the amp or it wont light up...the amp gives it the extra power it needs to be lit because the louder i play musisc the brighter the LEDs. No problems so far and have this set up for almost a year now
what input would you suggest?
frag_bomb (author)  derbert5 years ago
at that resistance probably not sound, lower your resistor value and try with whatever musical device you can plug it into
Its not a transistor its a resistor you are talking about and perhaps it should of been mentioned that you need an NPN transistor not a PNP one.
yh yh cheers my bad. my transistor is the kind detailed. just wondered if the resistance was wrong and needed changing.
zoltzerino5 years ago
would a bc108 c work??? ZZZZ
frag_bomb (author)  zoltzerino5 years ago
see no reason why not, try it
I have just made the 'standard' JT I have no resistor before the base and I am using a bc108c. It only works with AAAs not AAs it just flickers with AAs. Current overpowering tran??? ZZZZ
frag_bomb (author)  zoltzerino5 years ago
try it with a resistor you need it to determine the current output of the transistor ....... i think
I made a MBT and it works, I even split the audio so i can listen and flash! Although it only flashes at a painfully high volume, is it my bc108 (do I need a low voltage transistor) or have I got the wrong amount of turns on my toroid??
frag_bomb (author)  zoltzerino5 years ago
Well done on making it, i think a lower voltage transistor would be best you want a lower emitter - base voltage to get it to flash at lower volume.
ok thanks
Biotele5 years ago
can you post a video of the LED flashing to the music?
frollard5 years ago
The solder DID ruin the photo - the camera focused on the solder instead of the project! ....USE MACRO MODE FOR CLOSEUP PHOTOS!!! :D If you don't have macro mode, then since its gonna get sized down by instructables, then take a picture, in focus, from farther away - then crop it. Pictures aside - neat project! Extremely low lowpass filter :D
Kokkan frollard5 years ago
We have a photographer in here RESPECT
Restecpt. Ali G... IN DA HOWS!
ironsmiter5 years ago
hmm. I wonder if anyone knows(or knows how to calculate) the resistor value to put one of these IN-LINE with a headphone speaker. I'm thinking a nice blue led synced with the music on my headphones. I get music, and the people around me get a light show!
Emsaid5 years ago
the solder didnt ruin anything... ...the picture already was ruined! (Just kidding!!) Very cool!
hominid5 years ago
Very good and clear. I like the new use for the JT. Thanks.