Hello:

Got a small project I am working on and need a visual indicator of when voltage changes (about 8 read points). So, instead of setting up 8 VOMs and running back and forth, I'd like to use a few multi-color LEDs to visually indicate the voltage used.

First, I was thinking of something like this:

http://elexp.com/opt_rgbc.htm

But I am not sure if it is best for this project. I only need 3 colors. Ideally, the initial voltages with same colors:

(the colors are not set, they can be any two colors)

0-6V = Green color
6-9V = Green & Red Color = Yellow
9-12V = Red color

So a simple two-color LED would be fine that I could power both colors at once.

What I'd like help with is building the circuit turn on/off these colors at those voltages ranges. Hopefully, as small as possible. I don't have any circuit tools for assembly of them, but can invest a bit if need be. So larger components that can be soldered using hand tools is preferred. Not looking to spend a lot of time on it. Just need some lights!

 

Read this datasheet.

Oops. 1 number off. Look a the next one.

 

The LM3914 is linear. You could set it up for 1.5 or 3V steps in dot mode and combine outputs to a 3-color LED.

http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=lm3914&fileType=pdf

http://www.google.com/url?sa=t&sour...vh0N4H&usg=AFQjCNEZStMvaHNyTztaoQShFgjLj1V8Bg

 

Those are interesting. I see the typical use and trying to fit that into my use.

Would someone be kind as to describe how I would use it, briefly?

 

Check my edit above. You could have several of the output steps feeding the same LED instead of separate LEDs on a bar graph.

 

Ah, thanks for the edit! Got the idea now of how it works. Yeah, was hoping to avoid an IC but looks like the only way. Time to dust off my 20 year old skills of soldering and heatsinking.