A wearable sound-to-light display, without a microprocessor - the Musicator Junior.

Smaller than the 9-volt battery that powers it, the Musicator Jr. displays the sound it 'hears' (through the Electret Microphone) as fluctuating light bars.

Small enough to fit in your shirt pocket, it can also be placed on a flat surface to monitor the sound levels around it.

An alkaline battery will easily power it 20 or more hours.

Step 1 The parts needed

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The 'brains' of this project is a LM358 general-purpose op-amp which costs under 30-cents. The first half of the circuit is an amplifier which boosts the 500-micro-volts from an electret mic to about 1-volt. This level is generally called 'Line-level' and can be used to drive our LEDs, an audio amp, or even the input pins of an Arduino processor.

The second half of the op-amp is used as a voltage-to-current converter, which limits the brightness of the LEDs to 10mA or less.

The complete list of parts is below:

LEDs. Any combination can be used, as long as their total forward voltages is less then 8. For example, you can have up to 4 amber LEDs with 1.8v Vf.

Electret microphone - I got mine on eBay for under 25-cent
LM358 - Op-amp (8-pin DIP). Also available on eBay.
2N4401 - NPN general transistor (other audio NPN-types will probably work as well)
10k resistor x 5
2.2k resistor x 1
470k resistor x 1 (Can also be 330k as labeled in the circuit)
100-ohm resistor x 1
1uF capacitor
0.1uF capacitor
9-volt battery and connector
Perf-board and mounting parts.

Total cost: $3 or less.

Comments

[J-Five]

Here's one that I drew.

[Jim5975]

can you label r1, r2, c1 etc......

[J-Five]

what do you mean?

[Jim5975]

r1= ???ohms etc

[J-Five]

Sorry about that I misunderstood what you meant. Here it is

IC1 = LM358 - Op amp (8-pin DIP)
Q1 = 2N4401 - NPN general transistor
R1 to R5 = 10K
R6 = 2.2K
R7 = 470K
R8 = 100 Ohms
C1 = 1 μF ceramic disc capacitor
C2 = 0.1 μF ceramic disc capacitor

[Jim5975]

ok thanks

[J-Five]

No problem.

[indiantinker]

Awesome Instructable..i have done something like this using Arduino and Processing!
But this one is real portable!
Im making this one...
Cheers!

[qs]

Thanks! I hope you have fun building this simple project.

And check out my Arduino powered Level Display too!

[umfan110]

is there any way that you can split it into high, mid, and lows

[qs]

I have a couple of other projects that do that, including this one: http://www.instructables.com/id/A-Triple-Channel-Musicator-the-TriM/ and the Android driven Musicator: http://www.instructables.com/id/The-LED-Matrix-Panel-or-LMP-for-the-Arduino-micr/

Hope they're what you're looking for!

[umfan110]

This was exactly what i was looking for did you hook this up to a mic or to a 1/8 audio jack. Mine my iggnorance but what dose COM mean i never understood that i know there is left and right but com?

[qs]

COM stands for Common - if Red and White are the RIght and Left channels then the Common is usually the Black wire.

[AronC0816]

I have to agree with the two people above me. I can somewhat read schematics but this one confuses me. It would have made more sense if the rectangular shape of the op-amp was included and the interior circuits were shown inside that box. Then you could show each of the eight pins and what they should connect to. I tried to wire this up but it took me over an hour and it doesn't work. So apparently i did something wrong.

[thealeks]

would it be hard to use 6 mics that individually trigger 6 LED's?

thanks

[qs]

Nor too certain what you aim to do here - you could easily drive 6 LEDs using just the 1 mic and circuit here - why complicate things?

[thealeks]

i want to set up a small light show for my guitar, and i want each mic to be activated by a single string, so when i play, a light will light up for each string thats played

[qs]

I think you will find that, in real life, this setup will not be able to distinguish between the strings. one mic will pretty much 'hear' the same thing as its neighbor. It MAY work if you have an electric guitar and can extract the signals from each separate pickup before it goes into the pre-amp stage.

[thealeks]

i was hopin i could lower the sensitivity, maybe by giving the mics less power, and putting the mics right up to the strings, so they only pic up their designated string. im still learning so i dont know much about this stuff, so i dont know if that will work or not

[qs]

The only way to find out is to build one and see if it can be mounted to exclude sounds from other strings.

An alternate approach is to use the approach used in this circuit which splits the input into 3 distinct (low, med & high) frequency channels to indicate the pitch, rather than the string played.

[thealeks]

i thought about that, but then the lights wont sync up with the strings, but the ideas not out.

last question, how would i change the sensitivity of the mic?

thanks for all your help, by the way, i appreciate it

[qs]

The 470k resistor named "Level" controls sensitivity - the lower its value, the lower the gain. it can also be a 500k adjustable resistor so you can play with the setting that works for you.

[thealeks]

ok awesome. thanks for your help. ill let you know how it turns out!

[phevtron]

how sensitive is it to sounds?

[qs]

With these electret mikes, it will work with low-power speakers played at regular volume. The sensitivity can also be adjusted to be about 10 times higher, but background noise will then become a problem.

As I mentioned, any sound you can hear clearly, it will display.

[phevtron]

thank you for replying :D you just offered a teen an amusing yet attractive decorative idea :P

[musick_08]

instead of a microphone, could you put on a 3.5mm jack so the lights flash to a music source?

[qs]

Check out my other circuit which uses only a handful of parts and takes the output from an Earphone plug to flash an LED. It was designed to use a USB supply, but any 4.5-6 volt supply will also work.

Circuits that only use a single transistor suffer from 2 major problems: they do not work unless the volume is cranked way up, and they distort and may even damage the sound source.

[musick_08]

I think this would work. i wanted a small circuit that could be used with a small battery source if needed. thanks

[The Insignificant User]

Try checking out this one: http://www.instructables.com/id/Music-LED-Light-Box/
I honestly think the circuitry on this one looks a bit simpler, but it should work for what you are thinking of.

[musick_08]

i've used the circuit for that on other projects, but i want one that can use a battery source for portability

[elijah_rippington]

i have built that circuit to run off a 9 volt battery by placing the LEDs in parallel, so its entirely portable.

[The Insignificant User]

Oh, I see. Well, I can't say that it would work for certain, but I've run several LED's off of 2 AA batteries with the proper resistor. I haven't used the transistor that was featured in that project before, but it shouldn't cause too much impedence, I think.

[sayray]

HI!! I am looking to create some inner light effects for a runway/hair show avant garde style... as in light would be glowing/flashing from inside the hair sculptures. Do you think something like this would work for it? Would it be bright enough for a dimly lit/ or dark stage? Could it be adjusted for more lights or brighter lights? Possibly flashing lights but w/out the music respose?? I am looking for a definate flashing/ good deal of light streaming out, not tiny rice lighting. What do you think?? Any help would me so so appreciated!!

[anarky2k]

ive made it....but my leds flash very dimmly and they have to be very close to the music source....ive gone over it and the only thing i have different is the transistor, i used a 2n2222a cause i couldnt find the other one.....could anytbody help me xS

[qs]

The PN2222 (the 2N2222 has a metal case) should be OK for 9-volts and the 3 LEDs used here but do not increase the voltage or current. Your problem may have something to do with the electret mic - read some of the responses below for fixes for dim light. They will probably answer your question. Some pictures and description of your build may help isolate the cause too!

[anarky2k]

jajaja thanks, ur right, the microphon didnt work, as soon as i put another one in it worked......noow i have a different issue....the leds dont turn off completly, they flicker alittle when theres no sound...any advice?

[qs]

First make sure you are not picking up noise from electrical equipment around you - or even hum from wall plugs (try a .1uF cap across the mic). If that doesn't fix it, you can lower the value of the 'level' resistor from 470k down to 330k. This reduces the sensitivity of the mic.

[mayur.phadte]

Thank You for dat humble help
I checked the wire at R3 as well as the wire no. 19(I didnt quite get you when u said R3 + wire 19) the leds go off when I remove it
I checked the wire no. 24 as well

[qs]

Then remove the (+) input to the second IC (pin 5 and #18 in the enlarged diagram below) If the light stays on - there is a problem with that part of the circuit - defective IC and/or wiring error.

Oh, and if you are running from a wall plug - it may be putting out too much noise - try with a 9v battery!