Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [lm3915]

A "Dot/Bar Display Driver". Drives 10 LED's at -3 dB per LED, for a range of 30 dB.

1
vote
3answers
1k views

Do output LEDs here need resistors?

Consider: Here is the schematic I'm trying to work around. My major question is about the LED bar graph I want to use, on the right side; does it need resistors? I saw three different versions of ...
1
vote
1answer
96 views

Precision Full-Wave Peak Detector component values

so, I am a beginner in electronics...hoping to find some help... here I've found a circuit that I want to use from LM 3915 datasheet..... but the problem is I don't have 0.2 and 0.47 Capacitors... ...
0
votes
1answer
294 views

Op amp LM324 as pre-amp to LM3915 LED VU Meter

simulate this circuit – Schematic created using CircuitLab I have made a LED VU Meter using LM3915 and added a low pass filter too. Then I've tried a basic op amp circuit using LM324 (inverting ...
-2
votes
2answers
111 views

VuMeter using LM3915 not working properly

I built a simple Vu Meter on a breadboard using the LM3915 IC following a tutorial found on the web, all seems to works fine and the final result is something like this: The only difference is that, ...
0
votes
0answers
216 views

whats the difference between a cascaded band pass filter and a normal band pass filter (Audio visualizer)

simulate this circuit – Schematic created using CircuitLab currently im building an audio visualizer i would like to know what is the difference between a cascaded 2nd order band pass filter ...
0
votes
1answer
369 views

LED bar graph driver with 12 pins? [closed]

I wanted to use a 12 LED bar graph with a LED bar graph driver but the the driver I know (LM3914) supports only 10 LEDs. Is there a similar driver IC with more out pins? The purpose is to use the bar ...
0
votes
1answer
302 views

make a 2 wire voltmeter w/led bulb display

So I've been working on a project for a while now and I'm looking to create a specific feedback for the user. What I want to do is to make a 2-wire voltmeter that operates similar to this one. (Click ...
3
votes
1answer
556 views

How do I make the LM3914 (LED) Bar-graph driver IC make the LEDs light up brighter?

Like I said in the title, I am using the LM3914 IC to drive a 10 segment LED Bar-graph. The actual subsystem has the signal pin on the IC connected to a capacitor, thus displays the amount of charge ...
1
vote
1answer
312 views

Which precision rectifier should I use for a 60dB LM3915 Vu-meter?

I want to make a 60dB Vu-meter with two LM3915 chips. In the datasheet is recommended to use an external precision rectifier and they give two type of rectifiers: half-wave and full-wave. My problem ...
0
votes
1answer
4k views

LM3915 VU Meter Not working properly

I built a LM3915 (Waiting for LM3916 to arrive) VU Meter based on Sparkfun's tutorial https://learn.sparkfun.com/tutorials/dotbar-display-driver-hookup-guide Problem is, when I plug the power, only ...
1
vote
4answers
1k views

Turn a transistor on when any one of nine LEDs is on using an LM3914

I'm wanting to turn a transistor on when any LED from LED2 through LED10 are on with an LM3914 in dot mode. Basically, I want the transistor to be normally off until at least LED2 begins to light (...
0
votes
1answer
2k views

Make three respective LEDs blink with an LM3914 in dot mode

I'm trying to figure out how to make in the below schematic, LEDs D2, D3, and D4 blink respectively while the LM3914 is in dot mode when their on state occurs. Basically this would act like a warning ...
0
votes
1answer
5k views

VU meter from line input or speaker input?

Is any of the the two following schematics for Line input? Or is it for the amplified signal that goes to the speakers? ( source ) ( source )
4
votes
2answers
974 views

List of LM Integrated Circuits?

Does anyone have / know of a list of all the LM integrated circuit packages available? The EE stockroom at my university recently reorganized and they cataloged several pages of part numbers without ...
1
vote
1answer
1k views

LM3915 to drive more LEDs / basic questions about PNP transistors in saturation

As a few others here, I'm trying to drive a few (10) LEDs from each output of a LM3915 vu-meter chip. I've read different posts, and it seems the universal recommendation is this great answer. I have,...
1
vote
1answer
373 views

What transistor if they are needed do I need to drive 5 blue LEDs on a lm3915 and how should I hook it up?

I am using an LM3915 LED driver in dot-mode. I would like to drive 5 blue LEDs (3.3V forward voltage @ 20mA per LED) per output. What type of transistor should I use to make this happen? And how do ...
0
votes
2answers
733 views

LM3915 questions about data sheet and operation

I am connecting the LM3915 to a PNP transistor to drive LEDs. I have it working in bar graph mode using one LED per output directly (no transistor). On page 7 of the datasheet, it looks like pins 1,...
1
vote
2answers
7k views

LM3915 Circuit how to adjust input level?

I have used the circuit diagram that is on page 2 of this datasheet and it works pretty much. I am getting the signal off the output of my computer which has been cut and then feed into my circuit and ...