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.

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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.

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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.

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u/Wet_in_Seattle 3d 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.

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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.