Electronic VU meter by LM3914 and LM3915

Here is High performance LM3914/LM3915 VU meter projects that widely popular can display with 20 LEDs on stereo or mono with 10 LEDs for all audio system.And can easily build and cheap you must happy when use it.

This electronic VU meter set is circuit that High performance and widely popular than 40 years.

This project is very easy, because use alone IC only and a few external components. The display system can drive directly LED up to 10 LEDs and display as light running is DOT or BAR as you want follows by Figure 1.

The working principle
electronic-vu-meter-by-lm3914-lm3915-circuit-diagram
Figure 1 Electronic VU meter circuit diagram by LM3914 and LM3915
The main in working of this circuit is LM3914N or IC LM3915N as suitable for your working. Which the external circuit is the same.

Note : You can see VU MTER with LM3914 or LM3915 in :
Let’s to build many VU Meter circuits with LM3914 ::

The difference of the two ICs is that:
1. LM3914N will display as amplitude of signal in Linear form.
2. LM3915N will display as amplitude of signal in Logarithm form.
Normally if use amplitude of sound signal we should use the LM3915N.

The input signal from power amplifier wil be entered through to Voltage Doubler circuit consists of C1, C2, D1, D2 to convert sound signal voltage to DC voltage and have amplitude are 2 times of the input signal. Then, insert single to input pin 5 of IC.

And next IC will compare the signal amplitude, to drive LEDs display follows amplitude of input signal as above.

The Mode selection in working of circuit. to display in Dot or Bar form. The ability do with connecting a switch to pin 9 of IC. Which if indiscreetly release the switch will display is bar form. But connected the switch to pin 9 together with a positive voltage, the circuit will display in the dot form immediately.

How to builds this projects.
First of all, makes the PCB layout in stereo or mono as you need. Secondly, solders all components into the PCB, as you see in Figure 2 (stereo form) and Figure 3 (Mono form). Caution: Polarity of LED must be placed correctly. If you reverse the polarity, the LED does not light.

stereo-electronic-vu-meter-by-lm3914-lm3915-pcb-layout
Figure 2 The PCB and component layout of Electronic VU meter on Stereo form.

mono-electronic-vu-meter-by-lm3914-lm3915-pcb-layout
Figure 3 The PCB and component layout of Electronic Vu meter on Mono from.

The parts list
IC1———————LM3914N, LM3915N
D1, D2—————–1N4148__ 75V 150mA Diodes
R1———————-10K Resistors 1/4W
R2———————-2.7K Resistors 1/4W
R3———————-3.9K Resistors 1/4W
C1, C2—————–1uF 50V electrolyte capacitors
C3———————-47uF 16V electrolyte capacitors
L1-L10—————–LED 2x5mm.

Note:
1. If you need print the PCB layout please check 200 dpi per inch on image scale.
2. If you not like this circuit please look at:

VU-meter circuits

23 thoughts on “Electronic VU meter by LM3914 and LM3915”

  1. Hi ODX,

    many thnaks for your great works.

    I’d like to know somethings more about the following vu meter “https://www.youtube.com/watch?v=Kt4xdCHKK5I”:

    1) in order to realize it did you use the mono configuration (with led in parallel)(Figure 3) or the stereo layout (Figure 2) or “Level indicator with 10 LED” that you post on http://www.pira.cz/enbar.htm?

    if you use the mono configuration or “Level indicator with 10 LED” could you let me know how can I wire 20 leds instead of 10 led as in figure 3?

    On your youtube video you say “20 LED’s (9 colors) wired in parallel for the plexiglass sheets and the arrays also wired in parallel”

    It would be great if you could you post some photo of front and rear with more detail of the PCB that you have made.

  2. Excuse me! i just wonder that aren’t the 12V burn out the LED as LED needs only 2V each.
    Any comment is appreciated :-)

  3. Hi. Mario. Thx for the interest. If you can post an email here I can send you a few more pix of the build and hopefully explain a bit more.

  4. Hi Daravuth. Some LEDs use around 2 V and some other colors use 3+ V. Yes the LED will burn when connected directly to a 12 DC source. I am currently running 6 V. on my tower BUT have run it with 12 V without any problems. I have no resistors attached to the LEDs to step down the voltage so I’m guessing there is some internal resistance on the 3914,5,6 that compensates for this.

  5. I would like a meter with a 0-2volts input signal reading. What resistor (s) controls the step levels between the led’s and how do I determine the values of the resistor? Can I use either the 3914 or 3915?

  6. Hey man! I just wanna ask if this project is capable of running on a 5v supply or simply usb powered vu meter?. any components needed to be replaced or none? thanks man! 😀

  7. I want to share my experience. LM3915 work well on 5volt dc. you can use 7805 make this voltage from 12volt dc. If you want to use more led ex two led or 4 led in pararel,you can use PNP transistor,wich the BASIS is conected to the pin IC.. don’t forget to give resistor from Basis to the pin ic. 1 k ohm is fine. Emitor of transistor can be conected on 12volt dc. but the LM3915 conected to output 7805, of course 5 volt in order to make the IC LM3915 not burning or overheat. the 7805 should be conected with the heatsink. hope helpfull

  8. Sir I want to make 40 led vu meter using 4×3915. Can any one tell me that how to connect multiple ic 3915/3916. Please help. Thanks in advance!

  9. Well BOB.. It looks like some people have no spelling skills either….”gramical”??? Now there’s a new one to think about.

  10. Hi guys

    i hve dne ths project .as per the above circuit and same components .its cooll
    …………..

  11. Hi there

    Can you tell me – pin #9 connected w/ something or not? I’ve checked datasheet and it says that pin # 9 should be connected to pin #3 through the switch

  12. ELatestark…Pin # 9 does not need to be connected to anything BUT if you wish to display DOT mode shorting pins 3 and 9 (using a switch) will allow you to do so. If pin 9 is not connected your display will show BAR mode. Wiring in the switch allows you to choose 2 different display modes.

    Hope this helps.

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