# LM3914 - Expanded Scale Voltmeter - Help!

#### joe426

Joined Aug 11, 2009
39
I'm attempting to build a battery monitor using 10 LEDs to indicate voltages from 4.25 to 5v using an LM3914 dot bar display driver. However, after 5 hours of research and examining the links below, I still can't figure it out. Any guidance is greatly appreciated. Thank you!

Resources I've attempted to learn from this far:

#### bertus

Joined Apr 5, 2008
22,276
Hello,

On page 9 there is an example how to expand the range.

Bertus

#### Jony130

Joined Feb 17, 2009
5,488
What is you supply voltage?

#### joe426

Joined Aug 11, 2009
39
Hello,

On page 9 there is an example how to expand the range.

Bertus
Yes, I've thoroughly looked at the documents I linked to above. They're really poorly written in my opinion and I'm having trouble following them (hence why I asked for help).

What is you supply voltage?
I have two available rails. ~9v and 5v.

#### Dippo

Joined Oct 24, 2011
8
Dave Jones from EEVBlog made a really great tutorial about a battery tester using a LM3914. It's on Youtube.

#### joe426

Joined Aug 11, 2009
39
Dave Jones from EEVBlog made a really great tutorial about a battery tester using a LM3914. It's on Youtube.
Yeah, I linked to that video in my original post. He does a good job overall, but is still confusing about customizing a range.

Isn't there a simple set of equations with resistor values? I don't see why this is so difficult.

#### Jony130

Joined Feb 17, 2009
5,488
This circuit should do the job

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#### joe426

Joined Aug 11, 2009
39
This circuit should do the job
It will work for 4.25 to 5v? Is that what you're saying?

Last edited:

#### Jony130

Joined Feb 17, 2009
5,488
It will work for 4.5 to 5v? Is that what you're saying?
Yes, It will work from 4.25V to 5V As you mention in your first post.
But you can easily adjust the range by using a potentiometer.