Hello guys, I designed a 3-bit DAC which outputs a voltage range of 0-10V .To indicate the voltage intensity (Analog output) I added a LED at the output .I want the LED to start very dimly when I input 001(binary) to brightest(111 binary) but I can't achieve this. For 001 input its very dim but for 010 it is very bright . I can't use microcontroller in this project for PWM.Any method to indicate the output voltage intensity visually using least number of components?

 

Post a circuit diagram that shows how you're connecting this LED; without that, we can't help you much.

 

Post a circuit diagram that shows how you're connecting this LED; without that, we can't help you much.

Here is the schematic

 

You could drive the LED with a current drive instead of a voltage drive.
This would make the LED current proportional to the voltage, eliminating the LED threshold voltage and non-linearity of current vs. voltage effects, which are what's causing the large observed change in brightness with a small change in voltage around the LEDs threshold voltage.
That would make the light output more proportional to the DAC output voltage.

That would require the addition of another op amp and a few resistors.
Would that be acceptable?

 

You could get fancy and use a LM3914 to drive an array of 8 LEDs as a bar-graph.

 

You could get fancy and use a LM3914 to drive an array of 8 LEDs as a bar-graph.

@Alec_t thanks man, I didn't know about this IC , I'll have to check if it is available

 

You could drive the LED with a current drive instead of a voltage drive.
This would make the LED current proportional to the voltage, eliminating the LED threshold voltage and non-linearity of current vs. voltage effects, which are what's causing the large observed change in brightness with a small change in voltage around the LEDs threshold voltage.
That would make the light output more proportional to the DAC output voltage.

That would require the addition of another op amp and a few resistors.
Would that be acceptable?

Yes this is acceptable, in fact I have one unused opamp in the same IC , can you give me the schematic for the connections please?