VU meter with zener diodes?

[Braeden Hamson]

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!

 

[kellys_eye]

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.

 

[Bluejets]

Different color leds have differing voltage drops that you may be able to use to your advantage.