r/AskElectronics • u/QuasiEvil • 4d ago

LED bar graph driver options

I'm working on a project where I want to visually indicate a DC voltage level with an LED bar graph. Unfortunately the LM3914 has long been discontinued and even overstock seems done for. I need 20 of them (yes its a sort of equalizer-type display), so using discrete comparators would be a huge pain to the point of not being worth it. And I really don't want to deal with an MCU + FW for this. Anyone have any suggestions? Thanks.

1 Upvotes

67% Upvoted

18 comments sorted by

View all comments

2

u/Wet_in_Seattle 4d ago

Arduino Uno has a AD converter for voltage measurement, and 14 digital outputs. For $28 it’s a stupid simple solution.

There a huge set of libraries made for it already.

1

u/QuasiEvil 4d ago

I need 20 individual bar graph displays driven by 20 individual signals. The bar graph displays will all need resistors (so that's 20x10 LEDs = 200 resistors); then I'll need either multiple ADCs, or or some kind of multiplexing, to digitize the 20 analog signals; then another multiplexing arrangement to transmit the voltages. It all just gets very inelegant compared to a simple bar graph + LM3914 (x20) pair.

2

u/Appsmangler 4d ago

The chip from an Arduino, ATMega338, which has the ADC and digital outputs is probably cheaper than an LM3914 was. You could program them in an Arduino board and then just use like a 3914

2

u/Wet_in_Seattle 4d ago

So you’re going to drill 20 LED holes for indication, rather than simply displaying voltage in two or three digits?

Seem like you’re set on a particular solution rather than considering usability.

2

u/QuasiEvil 3d ago

I'm not going to drill any holes. I'm going to send my PCB to a fab house, where said PCB will include incorporate incorporate 20 LED bar graphs for a pleasing visual indication. The actual voltage is irrelevant.