• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Analogue Signal to Number of LED diodes on


New Member
Dear all,

I am currently building simple control system for a simple machine. Machine has Dial composed of 12 LED diodes that are arranged in a circle and I have only one output from my controller (voltage). Based on the voltage at the output of controller I would like to turn on discrete number of LED diodes .

For example:

0-2V - only 1 LED diode on,
2V-4V - 2 LED diodes on

I can do simple automation with simple PLC but I am not skilled in IC design. In my noob opinionhowever this would require some simple IC. Can anyone who is skilled in this give me answer whether this can be done and perhaps if anyone has seen any instructions how to do this sort of thing online? Any advice is appreciated.



Well-Known Member
Most Helpful Member
There used to be off-the-shelf ICs to do exactly that, complete with LED current control; eg.

What you can do is emulate that with some LM339 quad comparator ICs and a few resistors.
This is the basic concept, just make the series resistor string long enough to give the 12 different steps and divide the input voltage down with a couple of resistor (or a pot) so the maximum input to the 339 is somewhat below the IC supply voltage.

And use separate resistors to define the LED current.



New Member
Thank you so much. Ill try to make the LM3914 working. It is readily available where I am from.


Latest threads

EE World Online Articles