I want to do a comparator circuit with LEDs as output to show the voltage difference.Im using LM339 for now.Is there any other comparator which can drive more than 4 LEDs.

 

You can use a NPN or a PNP transistor driven by the LM339, and it will drive more than four LEDs. I suggest the use of a 2N3904 if you wish to use a NPN, or a 2N3906 if you wish to use a PNP. If you use a NPN, the LEDs will light when its input is driven high. If you opt for a PNP, the LEDs will light when its input is driven low.

 

Lanz,
Would you please attach a schematic of the circuit you're considering as it is now? Having a schematic available is worth thousands of words.

.png format is preferred; they are not "lossy" like .jpg images, and .pdf files take too long to load.

Use the "Go Advanced" button, and then "Manage Attachments" to navigate to where the image is stored on your computer.

 

Lanz,
Would you please attach a schematic of the circuit you're considering as it is now? Having a schematic available is worth thousands of words.

The circuit almost like above.

 

The IC you're looking for is an LM3914; it has a linear scale. There is also the LM3915 and LM3916 for logarithmic display and VU meters.

Information page: http://www.national.com/mpf/LM/LM3914.html
Datasheet: http://www.national.com/ds/LM/LM3914.pdf

If you give a bit more information, like your source voltage range, and what are the desired threshold levels for the LEDs, we can help more.

 

I dont know how the circuit i attach work?
But as far as i can see,the LED will be ON when the desired voltage (High and Low) reached at the input pin.
What i need is when its
3V=LED 1 will be ON and other LED OFF
6V=LED 2 will be ON and other LED OFF
9V=LED 3 will be ON and other LED OFF
12V=LED 4 will be ON and other LED OFF

But for VU based IC,when its
3V=LED 1 will be ON and other LED OFF
6V=LED 1&2 will be ON and other LED OFF
9V=LED 1,2&3 will be ON and other LED OFF
12V=All LED ON

Am i correct?

 

I dont know how the circuit i attach work?

Actually, it won't work properly.
There is no fixed voltage reference. So, the voltages across the resistor divider for the noninverting (+) comparator inputs will change along with the inverting (-) inputs. So, the only way you'll see a change in the outputs is by changing the setting of Rv.

But as far as i can see,the LED will be ON when the desired voltage (High and Low) reached at the input pin.
What i need is when its
3V=LED 1 will be ON and other LED OFF
6V=LED 2 will be ON and other LED OFF
9V=LED 3 will be ON and other LED OFF
12V=LED 4 will be ON and other LED OFF

Then you need a window comparator for each LED.

But for VU based IC,when its
3V=LED 1 will be ON and other LED OFF
6V=LED 1&2 will be ON and other LED OFF
9V=LED 1,2&3 will be ON and other LED OFF
12V=All LED ON

Am i correct?

The LM3914, LM3915, LM3916 IC's have a variety of options. They can work in "dot" or "bar" modes, and there is also an "exclamation" mode; a combination of dot and bar.

 

Then you need a window comparator for each LED..

Only now i know its called window comparator for this kind of situation(circuit).

The LM3914, LM3915, LM3916 IC's have a variety of options. They can work in "dot" or "bar" modes, and there is also an "exclamation" mode; a combination of dot and bar.

Im impressed.Interesting IC.Really need to be experimented.

Thanks for the info Sgtwookie.Really appreciated.Do u have any related circuits?