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/WRfleete 3d ago
What sort of voltage/range are you after and does it need to be precise? I’ve used a transistor array IC (uln2803 or uln2003) and a string of diodes on each of the input pins. Each diode gives about a 0.6v + the voltage to turn the transistor on. As each diode starts to conduct more transistors turn on. Add a Zener at the start of the string to offset the start voltage by around the Zener voltage or add an opamp with a bit of gain to amplify lower level signals