H2O spectrum analyser

[Ray] noted that spectrum analyzers have become a favorite project for FPGA evaluators and sent in his groups version from 2004. His team used a combination of MatLab, an Altera FPGA and sixteen pumps to produce real-time sound spectrum output.


  1. Rich says:

    the effect is less than desirable due to water physics

    my fave remains the flaming spectrum analyzer

  2. Matthew says:

    rich: this can be totally negated by playing the music with a slight delay, with regard to the analyzer. I think it’s a dope idea.

  3. yeah… as long as the “source” isn’t live there’s no reason that the audio output can’t be delayed to sync up with “water physics”

  4. Tuckie says:

    except for the fact that the flame one isn’t really a spectrum analyzer

  5. why not solenoid valves instead of 16 pumps?

  6. luigi517 says:

    he should give each pump its own reservoir with differently colored water in each

  7. Jeff says:

    It’s the Bellagio, writ small… very cool.

  8. Rich says:

    yeah delay idea would definitely help but it doesn’t change the fact that water falls at a fixed rate (too slow) that you can never change.

    i was thinking about this thing today and i think that you could tinker with nozzles and pressure ranges to achieve something less sloppy tho.

    if anything, i think that this rig could be reincarnated as something other than a spectrum analyzer to great effect.

    alas, ’tis true that the flame scope is not a spectrum analyzer at all. i love how simple it is tho. plus, FIRE. =D

  9. Ray says:

    Originally we wanted to use solenoids but the ones we wanted were $40-50 each and that added up quickly. We were also concerned that they may be very loud.

    Some of the delay is due to the capture time within Matlab. It had to sample for a brief window, process the FFT, and then send the data to the FPGA to generate the PWM signals. If we could’ve sent an audio signal straight into the FPGA through an A/D and processed an FFT there it would have been much quicker.

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