LM3914 Help

[dacflyer]

I can usually manage my way thru on these things, But i need help on this one..
Is it possible to make a SOC volt meter for 24v use. I know the chip is 15v max, but i figure with a regulator and isolated input it can be possible.
I'm looking I think for a 3volt swing ?
my low volts would show 0% SOC @ 23v and 100% for 26v.
I'm looking for low volts adjustment and high adjustment ( 2 calibrating pot ? )
I found this one for 12 use, but i need something for 24v use..

https://www.circuits-diy.com/battery-mo ... lm3914-ic/
.
.

[dyarker]

Actual spec sheet
https://www.ti.com/lit/ds/symlink/lm3914.pdf

max supply is 25V and measure input(s) protected to 35V.

Regulate supply to 15V - 18V. Voltage divide input by 2. That will give a 26V high end input, while staying safely away from IC maximums.
(half of 26V is 13V)

Cheers,

[dyarker]

Will this stay connected to battery full time and continuously on? Or with a momentary "on" switch?

[Janitor Tzap]

Hey Dacflyer,

Have you looked at these?

https://www.allelectronics.com/item/bt- ... ter/1.html


Signed: Janitor Tzap

[dacflyer]

Will this stay connected to battery full time and continuously on? Or with a momentary "on" switch?

Most likely stay on all the time...

[dacflyer]

Hey Dacflyer,

Have you looked at these?

https://www.allelectronics.com/item/bt- ... eter/1.htm

I have, but they are not programmable.. they just have some preset stuff, and wouldn't be accurate enough for my use.

[dyarker]

Most likely stay on all the time...

Short time I would have suggested two 9V batteries in series through a momentary contact switch to pin 3 of LM3914.

Full time calls for a voltage regulator from BUT (battery under test). I'll modify image from post 1 and come back.

Cheers,

[dyarker]

If it looks okay, I'll go to spec and recalculate the resistors.
Unless you want the fun

[dacflyer]

Dacflyer.png
If it looks okay, I'll go to spec and recalculate the resistors.
Unless you want the fun

That would be awsome.. I wish there was a cookbook on this LM3914/15/16 series of chips..
I could think of so many thngs to make, but i can't get enough understanding of this things, even from the data sheet..
Bout the best i can do is like the VU meters. and some basic volt meters, but nothing specialised like this one i am thinking of..

[Janitor Tzap]

Dacflyer.png
If it looks okay, I'll go to spec and recalculate the resistors.
Unless you want the fun

That would be awsome.. I wish there was a cookbook on this LM3914/15/16 series of chips..
I could think of so many thngs to make, but i can't get enough understanding of this things, even from the data sheet..
Bout the best i can do is like the VU meters. and some basic volt meters, but nothing specialised like this one i am thinking of..

Radio Shack had the "Engineer's Notebook".
By Forest M. Mims III
1980 Edition
Cat #278-5001
It has circuits for the LM3914 & LM3915.
{Pages 110 to 113}.

But here's one I found online in a PDF.
Here is the 1992 Edition.
It has circuits for the LM3914, LM3915, & NSM3916 VU Meter Module.
{Pages 106 to 110}.
http://www.zpag.net/Electroniques/Kit/T ... tebook.pdf


Signed: Janitor Tzap

[dacflyer]

I'm sure we all miss Mr. Mimms. I have one of his books, I think it was the 2nd one ?
Always had some interesting things in there..

[dyarker]

LT1084 spec sheet https://www.mouser.com/datasheet/2/609/ ... 269789.pdf

Could somebody double check my numbers please.

dacflyer, should keep you busy for a bit.

Cheers,

[CeaSaR]

Forrest is still a member here. You may get lucky and catch him via PM. He was also doing his Puzzlers and had a Favorites section, both listed under Workshop, for Jameco.

If you need a calculator for the LM3914, there's plenty on-line.

[dyarker]

If you need a calculator for the LM3914, there's plenty on-line.

I hope I did it right and am done.

For example, LT1084 sheet says 10 mA minimum load and Out to Ref is 1.5V. A few clicks on Windows calculator I had resistor values.

((R1 may need to be 9.31 kΩ instead of 14.7 kΩ.))

Cheers,

[dacflyer]

thanks, I'll get to tinkering on it soon...Just need to scrounge a few parts 1st..