Tube displays are great way to make electronics look vintage. There are tons of nixie clock projects, but not so many that uses tube bar graphs that usually are used to display radio signal strength. Microsyl shares a nice project where audio spectrum analyzer uses right of these tube graphs.
the core of analyzer is an ATmega644 microcontroller which has enough to run FFT code borrowed from Chan. In order to make it look real time he had to overclock AVR to 32MHz. Calculated result were sent to four 2 channel digital pots. Further signals are passed through opamps where signal offset is adjusted and amplified to match tube scale.
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