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VU meter with zener diodes?

Discussion in 'Electronics Homework Help' started by Braeden Hamson, Jul 9, 2018.

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  1. Braeden Hamson

    Braeden Hamson

    220
    13
    Feb 18, 2016
    Hello guys,
    For my electronics course I've been given an open ended problem to create a light show that reacts to music. I'm going to use some filters to have an analog voltage output proportional to the amplitude of the frequencies in that band.

    I don't have any questions about that portion, however I wanted to create a VU style effect with LEDs on the output of each filter. I'm aware of the LM3915, however my project description says that I should stick to simple components.

    I've been looking around online for a way to do this with passive components and I think I'll go for a set up that uses zener diodes of various breakdown voltages ( I think that's the name ) Say, 2v 4v 6v 12v, at each of these voltages an LED would turn on. Granted I'd use a voltage divider on the output of each zener diode in order to give the LED the proper voltage.

    My question is, would you consider this a good way to do this? Or do you know of a better way? My definition of good would be few parts, and low power.

    Thank you as always!
     
  2. kellys_eye

    kellys_eye

    4,276
    1,146
    Jun 25, 2010
    A simple chain of diodes (0.6V drop across each) as the reference inputs to a load of comparators (or switching transistors) would 'simulate' the LM3914 - you'd need to use a resistive chain with values suited to a logarithmic spread to get the LM3915 functionality.
     
  3. Bluejets

    Bluejets

    4,090
    857
    Oct 5, 2014
    Different color leds have differing voltage drops that you may be able to use to your advantage.
     
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