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LM3914, LM3915, LM3916 Differences

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I have read through the data sheets for the series of VU meters and from what I can tell, they are all basically the same except that the LM3914 displays based on a negative input voltage, and the other 2 display based on positive input voltages. Based on that, what is the main difference between the LM3915 and the LM3916, and which one should I buy?
 

chemelec

Well-Known Member
All 3 Are Basically the Same and ALL are Positive Voltage Inputs.
The DIFFERENCES are:

The LM3914 is LINEAR Display
The LM3915 is 3db increments, Log Display
And the LM3916 is a VU Meter Display. (-20 to +3db)
 

audioguru

Well-Known Member
Most Helpful Member
They all use the same 10 LEDs for their display.
The difference is the amounts of input voltage between steps.
 

chemelec

Well-Known Member
So the only difference is the type of display that they use?
The LM3914 is Typically used to create a Voltage display using 10 LED's

The LM3915 and LM3916 are Typically used to Display Audio Signal Strengths using 10 Leds.

The Real Question is: WHAT do You want to Create?
 
An audio power meter, although I ran into a problem with part of the design. The circuit has 4 display modes; Dot, Bar, Dot with delay, and Bar with delay (delay meaning that there is a second VU meter connected to the LEDs in the same way as the first, but it's peak detector has a higher capacitor). The problem is when I switch to the 2 delay modes, the 3915 working the "delay" LED is not bright enough to see at a respectable distance, and if it's left alone long enough it begins to mess with the regular VU meter. The regular VU is connected as the "Low cost 60dB display" shown in the data sheet. I'm thinking that connecting R-Lo of the higher meter to R-Hi of the lower meter then I might be able to simplify the design a little bit.
 

audioguru

Well-Known Member
Most Helpful Member
The brightness of the LEDs is determined by the current from pin 7 to ground.

About 45 years ago I made a 60dB audio level meter with two LM3915 "modules" that were made by National Semiconductor.
Each module has a small pcb with the IC covered in a black blob of epoxy and has an LED strip already connected.
 

Dean Huster

Well-Known Member
I think that for 1965, that would be the razor's edge of the cutting edge for both IC and LED technology. In 1965, LEDs weren't even as reliable as incandescent lamps and ICs weren't sophisticated beyond second-generation digital logic and simple linear op amps. 7400-series TTL wasn't really prevalent until the early 1970s.
 

chinmoy1955

New Member
I think that for 1965, that would be the razor's edge of the cutting edge for both IC and LED technology. In 1965, LEDs weren't even as reliable as incandescent lamps and ICs weren't sophisticated beyond second-generation digital logic and simple linear op amps. 7400-series TTL wasn't really prevalent until the early 1970s.
I doubt that LM3915 was even born in 1965!
 

audioguru

Well-Known Member
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Here are the NSM3900 modules made by National Semiconductor that I bought in the 60ies. They had an LM3915 surface-mounted and a surface-mounted strip of 10 red LEDs.
Today, the LM3915 and LM3916 are not made anymore and the LM3914 is available only in a tiny surface-mount package.
 

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