Good day,

I am trying to add a power status led to my circuit.

I have a input voltage range from 24v to 9v.

Now when my board as power i want a small green led to light up so that i can see that the board has power.

But i am not sure how to do this with the potential of different voltages.
and i don't really want to add a voltage regulator just for the power LED.

Is there a way in which i can do this?

Thanks

 

1. Use high brightness LED + 2.2K or 3.3K resistor. There will be difference in brightness but usually this is neglible for indication.

2. Use a Z-Diode to clamp voltage.

 

thanks,

2.2k resister worked

 

Zapno ...

This is a common problem. I also recently had a system where I needed to drive an LED over a wide range of voltage without being able to see the difference in brightness. The simple solution is to drive the LED with a current source. You get constant brightness regardles sof the voltage (withing limits of the current source).

An LM317 makes a very easy current source. Just look in any LM317 datasheet and you'll find a sample circuit. And of course there are lots of other ways to make current sources.