Continue to Site

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.

  • 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.

Calculating resistors for LM3914

Status
Not open for further replies.

m.nowak

New Member
Hello all! I am new to this site but have been reading a lot and learning a lot to from this forum.

So, I have a question. I have a LM3914 which I wan't to use to monitor between 0.75V and 0.85V. I am having some troubles getting the resistors right for this build and hoping someone here can help me out.
 
What value LED current do you want? That value (Rx) will determine what R1 (as per the datasheet) should be. R2 will be zero. Make R1 from three resistors in series, having a total equal to Rx. The series string will give two tapping off points for 0.75V and 0.85V if the resistor values are suitably chosen. Connect Rhi and Rlo to the tap points respectively.
Example:-
Rx = 1k25 (for LED current ~10mA).
Choose 750R, 100R, 390R to make up R1.

You may need to tweak those values slightly, allowing for chip and resistor tolerances.
 
Last edited:
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top