LM3915/LM3916 VU Meter

The LED VU Meter was the height of late 80s boombox technology. This instructable will build one out on the breadboard. Who doesn't like blinking lights...

I have a bigger project in mind and will post instructables of each piece and tie it all together at the end.

Here is the live action video:

Step 1 Parts

You will need either the National Semiconductor LM3916/LM3915/LM3914, 2 for stereo...

-2x 1.2k Ohm Resistor
-Wire
-2x 10 LEDs or a 10 Segment LED Bar graph
-2x Breadboard, or just one big breadboard
-2x Stereo 1/8" jacks
-Optional 2.2uF capacitor
-Power supply anywhere between 3-25v

Comments

[Mathieu5555]

Since co'callaghan1 have not been answered, I still do not know what is the Vref, so I put a 10K potentiometer in place of 2 7.5K and 1.3K resistor.
Now I Can ajust the VuMeter. If the sound is not very loud I can raise the level. So its work perfect.
Pot 10K, first pin go to #7
Second to #8 on chip
and third on ground.

[uhclem]

For those looking to add a "power level" meter to a small amplifier (like a boombox) this circuit might be worth trying:
http://www.bowdenshobbycircuits.info/page11.htm#vumeter.gif

It uses the LM339 quad comparator. It needs more parts, but is overall much cheaper and easy to find.

[chainsawz]

im currently building a circuit like this; but the input isnt strong enough so im gonna use the LM386 to boost the input so more lights turn on... without it, only the first three lights turn on at maximum sound

[happywatt]

I have the same problem with an LM3914, but I didn't know what an LM286 is nor how it works, any advise?

[static]

Respectfully, and to state the obvious, simply use google. Also do the same search on on you tube. The LM386 is a small audio amplifier.

[radiorahim]

 Radio Raheem!!!!!!
Living large. Man, he even walks in stereo.
Love it.

[radiorahim]

 What is the red thing in each of the photos?

[reverser514]

well son, when a photon likes a diode A LOT, they make whats called an LED. haha the "red thing" in the photos is a bar graph, simply a bunch of LEDs in line with each other and packaged as one item instead of a bunch of LEDs.

[radiorahim]

Well old man, I think what we have here is a failure to communicate. Step 1, bottom of the frame, a red plastic thing. Is it some sort of probe?

[JohnBailey]

Yes. It's a hook probe. Same use as a crocodile clip, but much smaller.
Press the button (big end) and a little hook slides out to clip on a component lead or wire. Release it, and it pulls back gripping the wire.

[burton2663]

im looking for an actual schematic of lm3915 vu meter using 1w luxeon leds, im trying to use tip31c as a driver but the output of the 3915 is so little to drive the transistor. im using this cell charger than goes up to 8volts

[co'callaghan1]

Sorry about those last three posts. I've only got one question. Can you please explain what Vref is and what I'm supposed to do about it? Do I connect it the way it describes or what? It's just confusing because it does not appear to be connecting them. Do I have to do that?

[co'callaghan1]

(removed by author or community request)

[co'callaghan1]

(removed by author or community request)

[tqnata_1]

i want to know 2x 1.2k Ohm Resistor -W=?
-Optional 2.2uF capacitor =v=?

[faki]

Do I use the leds as they are on the schematic or I put a resistor for them ? I am using 10x1,8V LEDs

[reverser514]

yeah little information here...
(:D one lesson a day)

because they are 8v LEDs, and the chip only outputs at the most 5 volts (because we can't output more than we are given. (well we can, but that is WAY more advance than what we are doing here...) and under-powering an LED will not do any harm. Except mental harm because if the LED doesn't turn on, then you get confused out your mind of why it isn't...
(UH OH im breaking my one a day rule...)

THE SIMPLEST ANSWER IS ALMOST ALWAYS THE CORRECT ANSWER, AND MOST OF THE TIME, IT IS THE ONE MOST OVER-LOOKED!

[nak]

as they are works

[Werewolve]

I have 12V car battery. Where can i get the 3V for the Led's? or can i use 12V with a 620Ohm Resistor? Led: 2,25V 20mA

[reverser514]

OH THANK YOU FOR ASKING THIS QUESTION!

I had a couple of tweeters left over from a sub box I scrapped awhile ago. I took some good old wood, cut a circle out of it for the speaker, and left room for LEDs. My only problem is I don't feel like running a wire from the front of the car to the trunk.. maybe I'll just splice it in with my trunk light... :D then it will only turn on when the trunk is open!!! and the crowd goes wild on the thought!!!

[likeastone9999]

you can use 12 volt... but use a 330ohm 1/2 watt 5% tolerance... they work great for led's

[charlieb000]

get a 3v (or so) regulator..

[microOhms]

i love to invent or to make a device w/o planning like of those people who make an electric devices!!!!!!!!!!!!!!!!!!!!!!!11

[yashfau]

can u please show how you have connected the audio to this device ?

[bror89]

hey what's the difference with these two chips?
LM3915 IC chip LM3916 IC chips

[the_don125]

Both are logarithmic display drivers, the LM3916 is just better tuned for audio.

[zcrank]

N o Way. You Rocked the Siouxsie in the Video! Way Kool!!!

[Raiden19]

I was thinking, could you get this to run off a usb port 5 volts? If so you could use it on your pc. House the electronics in a seperate box and just have the visulisers showing, either side of your monitor for both channels.

[wootwootman]

is it possible to add a potentiometer in there somewhere to vary the sensitivity of the input?

[grampafish]

this same chip ie 3914 can be used along with a 555 and 4017 to make an led oscilloscope see schematic

[chance313]

I am interested in building something like this to put on my guitar, so when i play it on a dark stage it will light up. does anyone know a way to do this where i can wire it to the audio output. If it helps, i have active pickups.

[spinynormann]

how large is your input signal?

[alex7street47]

can u cascade the ic to 5(50 led) with 1 single input.... how the schematic?

[Zem]

 Is your parts list for two of them (stereo), or just a single one?

[fkuk]

http://i813.photobucket.com/albums/zz53/fkuk/Picture005.jpg?t=1260575391

hi

i want to know if this schmatic is correct and also i want to know the calculations behind this because i am doing this at college for a project

i want to know is there a way of working out at what step each led will light up at i have done the praticle result which is on the side but as part of my project i need to show some working and not of completed my project by trial and error

[j03tv]

Hey, Ive built 2 of these each with a LM3915 and LM3916 and they work just great, but my only concern is; If you look closely to the LED's when they light up, they flicker a lot!
I know they are supposed to more towards the top of the bar but the starting LED's should be solid. They are in Bar-graph mode also(Jumper pin 9 to pin 3).

Do you have a solution to reduce the flicker, like on commercial mixers and stuff? Those meters dont flicker.

[agis68]

where u get the bargraph leds??? any cheap place????

[DJNASHA]

(removed by author or community request)

[seligtobiason]

Sure you can, you can buy a ton of things that people make on instructables.com.... that's not the point, the point is using your own creativity and fun building and learning.

[happywatt]

I am brand new to electronics and have started with some simple circuits using transistors and 555 timers. Yes, I managed to burn up a few chips and lots of LEDs and some of the terminology is tough but I'm slowly getting there. Well I recently built a VU using a LM3914 dot/bar driver and I can't seem to get it to hook up to anything but a potentiometer. The chip is working both in bar and dot mode but I can't seem to get it to hook up to any form of music. I'm not totally sure I know exactly what I should be connecting the input to to get it to move with music, any suggestions or advise you can offer? Your assistance woiuld be greatly appreciated. Thanks,