Nixie Tubes for volume display

[wcrankshaw]

I'd like to do a build using an old nixie display tube wired to something that would correspond with the volume knob. with the volume turned all the way down the tube displays 0, and turned all the way up displays 9, etc. Any idea on how this might be accomplished?

[defaced]

There's probably an easier way, but the first thought that came into my mind was to use an MCUs analog to digital (ADC) capabilities to sense the out coming signal level from the MV pot and use that to decide which element inside the nixie to turn on. You could also use a dual ganged volume pot, one for the signal and another for the ADC input.

So the chain would be:
MV - MCUs ADC - nixie driver - nixie

If you use the MV as the input of the sensing circuit, you'd need to condition it to knock it down to a level where the MCU could use it. This may or may not work - I've never done it. Or if you use a dual gang pot, the conditioning is already there because you can simply feed the "top" of the pot with a MCU friendly DC reference voltage and get what you want.

[wcrankshaw]

Excellent, thanks. That's a lot more complicated than I was hoping it would be, but I had a feeling complicated might be the case.

[defaced]

There might be an easier way. Nixies existed long before MCUs, so there might be dedicated chips that you can find/salvage to do this, I just haven't been around the block enough times to be exposed to them.

[wcrankshaw]

I'll try to check into it a little more. I'm not sure I fully grasped what is required to use a nixie. I thought maybe each element would just react to varying voltages or something like that.

[defaced]

Nixie elements are discrete, so each number is energized individually.

An example:
http://www.decodesystems.com/nixie-book-fig2.gif
Nixie Displays

[Steve Conner]

Yes, nixie tubes have an anode to which you apply about 250V via a resistor, and 10 cathodes that are the numbers. You connect them to ground to light them.

Just use a 10-way rotary switch with a resistor string instead of a volume pot, and wire up a spare wafer on the switch to operate the nixie tube.

You'll only have 10 possible volume settings, but that's a small price to pay

[g1]

Very strange to see your post as I was just thinking about nixie tubes in tube amps this morning. I have an old multimeter/freq.counter with nixies as shown in photo.
Remember there is also a decimal point which can be used. Also if you used 2 of them you can say "but this one goes to eleven".
Other uses in an amp could be for average power out, % distortion, or output bias/current draw.
Good luck and hope to see pics of finished project.

[wcrankshaw]

I'd love to get that rolling sooner than later, but I've got another project on the table right now. My building sidekick and I are doing a Ryman Auditorium inspired 5G9 Tremolux. Going to be mahogany and have the pattern in the church pews in the Ryman carved in the sides. will also have stained glass panels running on the left and right sides of the front, as well as covering the back panel. Instead of a pilot light there will be lighting inside the chassis to illuminate the stained glass.

[Enzo]

Gee, how about a little pin spot in the back, shining through a gobo to project a glowing cross on the back wall of the stage?

[wcrankshaw]

that would at least up the price by $1000.