Dear SgtWookie,

I found your posting on the forum regarding the use of an LM3914 to drive an LED bargraph:
Quote:
Originally Posted by SgtWookie
Attached is a schematic of a 0v to 5v 10-LED Bar Graph voltmeter made using a National Semiconducor LM3914 IC and a 10-segment LED bar display, with a couple of resistors and a capacitor.

To change it to read from 0v to 6v, replace R2 with a 4.6k resistor. That's it.

You can power the circuit with a 9v transistor battery.

It does not get a whole lot more simple than this to build a 10-segment voltmeter display at home.

The schematic came from page 2 of National's datasheet.
The datasheet is available from this page:
http://www.national.com/mpf/LM/LM3914.html
Direct link to datasheet:
http://www.national.com/ds.cgi/LM/LM3914.pdf
Jameco supposedly carries the LM3914N-1/NOPB for around $1.55, but their server is down at the moment.
Jameco does not have a minimum order like many suppliers do.

However, I am needing to adapt the above referenced circuit to monitor between 11.3 - 13.1 volts. To Clarify, 13.1V -> all LED's ON. 11.3V -> 1 LED ON. Below 11.3V -> all LED's OFF. Is it possible to do this with the LM3914? Power would come from the same 12V battery. And if so, what adaptations would be required to the circuit you linked to:http://www.national.com/images/pf/LM3914/00797001.pdf?

Thank you!!

M.

 

Sorry, I don't have a good solution for you, nor time to work on one.

Perhaps someone else will have some ideas for you.

Here is one idea that is close to what you want: http://electroschematics.com/5952/car-battery-monitor-12-volt/
I have not checked it over nor tested it.

 

Actually the TRUE factory data sheet has all the info on making expanded scale meters with starting voltages other than 0V with the IC. It takes a bit of math but what doesn't?