Nixie VU meter

Most of my projects seem to deal with lights and music.  VU meters are not fashionable anymore, and the few commercial products I found don’t look too stylish at all. Therefore I decided to build my own using six Soviet IN-9 nixie tubes I had lying around.

The schematic is not too exciting at all. The audio input is connected to a MSGEQ7 graphic equalizer IC which I got from Sparkfun. Its output is processed by an Atmel ATmega88 microcontroller which sends commands to a M62359P DAC. The DAC outputs drive the tubes using a current sink described in “Driving IN-9 Neon Displays” by Dipl.-Ing. Jan Philipp Wüsten. The specific DAC was chosen because it was one of the few 8-channel DACs in DIP package that I could find without spending a fortune on shipping. Nixies are powered by a 1363 power supply. I had to connect a filter to its output (the large Teapo cap + a small resistor) to stop it from whining.

As the nixie tubes require a lot of space, a large enclosure was bought from TME. The mounts in the enclosure were quite far apart so the PCB became quite large. For that reason I etched the PCB myself, which I do quite rarely these days.

For future improvement I could check whether the MSGEQ7 output is linear or logarithmic – I’m thinking it’s linear as the sometimes the readings shoot way up without a great difference in perceived volume. Still, I think that the meter looks great and I’m quite pleased with it.

5 thoughts on “Nixie VU meter”

  1. Bonjour,
    Vendez vous votre vu mètre ?
    Si oui, quel en est le prix et est-il prêt à fonctionner.
    Peut-on le brancher sur une chaîne HiFi.
    Je cherche un vu-mètre à tubes pour brancher sur ma chaîne HIFI. En avez vous d’autres à me proposer ?

  2. What was your total cost on the project? Also, how much experience do you think a project like this requires?

    • It has been many years since I built the thing but the nixies and tee driver cost maybe 30 euros, 20 euros for the case and PCB material and 20 for the rest, so somewhere around 70 euros.

      The build is not very complicated, some basics about programming microcontrollers are needed as well as some basics about transistors. It is also good to understand how dangerous the nixie voltages can be.


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