Picture of USB-powered Musicator
This is a very simple Musicator that runs off the USB port. In its basic form, it only uses 4 components plus a single white LED. The 'star' of the show is the LM431 'Programmable Zener Diode' - which costs under 20c, so our project can be made for about a dollar in parts!

This allows us to double it up and have separate Left and Right channels, as shown here and below.

Step 1: Some sample videos

Picture of Some sample videos
As you can see, the circuit is very sensitive and is able to display even soft passages on low listening volumes.

um01234 years ago
Im confused on the schematic. Where does the usb come into play? where does the input from a music source go?

Sorry, i am a beginner in electronics.

P.S. Really cool instructable! i am excited to learn how to build it!
qs (author)  um01234 years ago
The music comes from the earphone plug of a player or laptop - see Step 6 for an idea of how they are connected.
very nice ...i will try this...thanks
Jmmaroli4 years ago
Great Instructable! Only one problem, I built this exactly and it works great, but how can I get the lights to flash with a heavy bass beat instead of with most vocals? Right now the lights hardly flash with the beat like they do in transistor based music light effect generators. Any ideas?
qs (author)  Jmmaroli4 years ago
You can modify the frequency response of this circuit by adding a ceramic (or disk) capacitor in PARALLEL with R1, the 15k resistor. The capacitor can range anywhere from 0.001uF (1nF [102]) for reduced reaction to higher notes; all the way to 0.05uF (50nF [503]) to allow only Bass notes.
Jmmaroli qs4 years ago
Thanks! Another thing that worked for me was to add a resistor capacitor low pass filter to the input, I'll try this though now.
infanati5 years ago
2 questoins. what did u make those tubes out of? and if i used a Tip31c, would that act the same as a LM431?
qs (author)  infanati5 years ago
The tubes are white drinking straw cut to 1" (2-3cm) lengths and crimped at one end after heating/melting.

The TIP series of transitors are low-gain trainsistors meant for switching 5 or more amps - and is NOT suitable for these applications, which requires the sensitivity to control less 1/30th of an amp.
   Despite its simple appearances, the LM341 has a dozen transistors inside that provide the functions used here. 
infanati qs5 years ago
so would it b possible to replace the Tip31 with a LM341 in this diagram?
qs (author)  infanati5 years ago
I've added a couple of steps above to show how to use this circuit with other voltages. They will be many times more sensitive than the circuit you showed.

Look it over - I'll be out of town for a bit but I'll answer any question when I have a chance.

If there is enough interested, I will add more circuits for other options and larger displays.
a LARGER scale version would be pretty cool. I've just ordered parts for some of your projects. I can't wait to get them up and running!
mathman474 years ago
Absolutely fantastic. I've just begun to dabble in micros & electronics, having received my Amateur Extra radio license at age 63. Hope I live long enough to understand and even develop projects like this. Great job = 5 * Can you identify the band in the first video?
qs (author)  mathman474 years ago
Thank you for your kind words.

I enjoy electronics - especially the bits that shine. My job does not allow me a lot of time to build complex project so I tend to design the simplest circuits that'll do the job. Check out my website and my other projects - you'll see what I mean.

The piece is Chantal Kreviazuk singing John Denver's "Leaving on a Jet Plane" from the Armageddon movie soundtrack. 
One of the best entries so far :) Superb example of KISS to create an elegant and well thought-out design.
qs (author)  thebeardedoneUK5 years ago
Thank you.

I'm fascinated by devices that combine Music and Lights, and this one worked out rather well.
godofal5 years ago
this is amazing :D one question though; i've build other "muzicators" but they all share the problem that when you turn up the volume, they are way 2 bright. or, on a too low volume, theyr not on at all. is it any different with that programable diode?
qs (author)  godofal5 years ago
With this design, there won't be any 'drop out' on low volumes - if you can hear it, it will display it.

This Musicator will work until the phones get uncomfortably loud, but in extreme cases, a 1K pot can be connected across the input and ground, with the - side of the 1uF capacitor connected to the wiper.

The accuracy of this is very high. The last video of it driving both the LED and speaker is pushing it to its limits and it still shows excellent linearity.
godofal qs5 years ago
k, il try that, whenever i get those programable diodes :D