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LM3915 LED Bargraph Driver

Visitor

Well-Known Member
Many people seem to like this chip which hasn't be manufactured for some time. Jameco Electronics has them on clearance. This may be the last opportunity to get them from a reputable source.

Screenshot_20210720-122359_Edge.jpg
 

audioguru

Well-Known Member
Most Helpful Member
The price is crazy. I got some a few years ago for $1.00 each.
 

Visitor

Well-Known Member
Such is the way with obsolete parts.

The screencapture from Octopart shows Jameco is the last "general purpose" supplier to have any of these left.Screenshot_20210721-094027_Edge.jpg
 

Visitor

Well-Known Member
The LM3914 (the linear version, as opposed to the LM3915 log version) is still in production, but even so, it's not a cheap chip.

Screenshot_20210721-094753_Edge.jpg
 

gophert

Well-Known Member
Most Helpful Member
I have some of NI's original modules give away as engineering samples. They had on-board bar graph array on a small PCB. I was never sure if it was intended to be a product (as a module) or just an engineering sample of the LM3914. It came with its own datasheet and voltage (sense) input.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
Looking for a data sheet, I found these - complete modules for a far lower price?

The ICs are visibly marked as LM3915,whether they really are or not is another thing... The NS logo looks deformed.


Also on ebay:
 

danadak

Active Member
Easy to do this with a processor with an A/D. Most of the 3914/3915
features. And do many more segments. A little less LED current.
Even though 3914/15 say current regulated its not very precise or
matched. Easy to implement various modes like moving segment,
or moving blank segment, or even variable gap.....


Regards, Dana.
 

gophert

Well-Known Member
Most Helpful Member
Easy to do this with a processor with an A/D. Most of the 3914/3915
features. And do many more segments. A little less LED current.
Even though 3914/15 say current regulated its not very precise or
matched. Easy to implement various modes like moving segment,
or moving blank segment, or even variable gap.....


Regards, Dana.
Maybe with the LM3914 but the LSBs get a bit wonky with only 8 or 10bits of ADC resolution if you try to simulate the Log scale output of the LM3916 or LM3915.
 

audioguru

Well-Known Member
Most Helpful Member
I notice that the ebay "LM3915" has its numbers removed and the board is marked "L1103" instead.
 

gophert

Well-Known Member
Most Helpful Member
I notice that the ebay "LM3915" has its numbers removed and the board is marked "L1103" instead.
You sound like you actually expect it to work when you get it. Happiness is when expectations match reality. I don't see happiness in your future if you order one.
 

danadak

Active Member
Maybe with the LM3914 but the LSBs get a bit wonky with only 8 or 10bits of ADC resolution if you try to simulate the Log scale output of the LM3916 or LM3915.
Yes at 8 - 10 bits but we have processors now regular doing 12, and no shortage of
choices now to 20 bits. And 10 outputs is not exactly a precision way of representing
enough resolution for precision representation of a signal.

Regards, Dana.
 
Last edited:

schmitt trigger

Well-Known Member
Visiting TI’s web page, the LM3914 is nowadays only manufactured in a PLCC package.
The DIP package is gone, although one might still find some NOS stock.
 

Visitor

Well-Known Member
I only posted for those who want the LM3915, here is among the last from a reputable source.

I'm not recommending anybody use this part. As stated, there are better ways to accomplish this task and probably are cheaper to boot.
 

audioguru

Well-Known Member
Most Helpful Member
A little more than 54 years ago I bought some modules made by National Semi with an LM3915 chip in a "blob on board" and a strip of 10 dim red LEDs.
I have an LM3915 in a microphone circuit I made with 20 LEDs and a circuit adding 20dB to it. It shows the sound levels in my living room and has been there for at least 24 years.
 

gophert

Well-Known Member
Most Helpful Member
A little more than 54 years ago I bought some modules made by National Semi with an LM3915 chip in a "blob on board" and a strip of 10 dim red LEDs.
I have an LM3915 in a microphone circuit I made with 20 LEDs and a circuit adding 20dB to it. It shows the sound levels in my living room and has been there for at least 24 years.
Which version do you have?
I've had a bag full of them for years (given to me by a retired engineer). I've never found a project worth completing.
0E89352E-38A2-49F6-B474-E5B25689467F.jpeg


and from the same engineer, an early LED clock module from National Instruments (1978). The control chip is hidden below the LED module.

E4A8CB6F-0793-4E93-979B-99CE469FACB8.jpeg


And back side... (looks pretty sloppy)
714AFB82-1892-47B5-B8FD-0C627CA2D77B.jpeg
 
Last edited:

alec_t

Well-Known Member
Most Helpful Member

audioguru

Well-Known Member
Most Helpful Member
Hi Beau.
It is interesting to see that you made a VU meter circuit and are selling a kit with it.
When I was working, all my prototype circuits were sold at high prices and the only reward I got was a shaver for saving a huge company (Philips) thousands of dollars.
 

schmitt trigger

Well-Known Member
I also purchased a MA1026 LED clock kit from Digikey. This module was similar to the models gophert showed above, but with an additional LM334 one could add a thermometer option.

I had it for over 10 years, and then gave it to an engineering student.
 

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