## Step 6: Design: Display

A voltage divider cuts the signal down by 1/2 so it's range is between 0V and 6V. A low-pass RC filter smooths out the very sharp changes in the volume signal (when the level of the nixie tube is changed too quickly, the lit segment jumps out to the middle of the tube, rather than lighting from one end).

The nixie tube has 3 pins, an anode, a control cathode, and an auxiliary cathode. The anode is tied to the output of a high voltage power supply at around 125V. The auxiliary cathode is tied to ground through a 220k ohm resistor. As far as I can tell, the auxiliary cathode acts as a sort of pilot light, forcing the tube to begin to glow at one end first, rather than from the middle or the other end. The control cathode is the main tube, and the current through it determines the length of the tube that is lit. A high voltage NPN transistor modulates the current from the control cathode through a 470 ohm resistor and potentiometer (for tuning purposes). The base-emitter junction of the transistor has a forward bias voltage of about 0.65V that it needs to turn on, so an op-amp is used to adjust the signal for this.
Hey, <br><br>I try to build this nixie music equalizer for an technical-school-project. <br><br>Could you give me a calculation-formula for your voltage divider. <br><br>'Cause i choosed 9 bands which are: 60Hz, 150Hz ,400Hz, 700Hz, 1kHz, 2,5kHz, 6kHz, 9kHz and 15kHz.
<p>Thanks for the inspiration for making this. It's a little bit different in design but I got the idea from this Instructable :) https://www.youtube.com/watch?v=Wjvm_wbBNGc</p>
<p>TL3472 heats up.Did I do something wrong? or it should be ? Can I use the other half of op-amp? one - left side, second - right side. And connect 2=6 and 3=5 legs ?</p>
great instructable, but a little too complex for my tastes and chance that you're going to sell pre-built circuit boards?
I'm working on a smaller, modular, and cheaper version, which I might sell in a kit form or just make public on batchpcb.com so that anyone can get their own PCBs made.
<p>Did anything ever come of this?</p>
Please do, I'm sure you could sell quite a few!
<p>than can be replaced ts3704 ? prices are crazy...1pcs more then 2\$ (((</p>
<p>Looks good? Any way you could make it shoot out smoke to?</p>
<p>Great instructable</p>
<p>Great instructable, I can't wait to build it. Do you have, by any chance, a workaround regarding the log-to-lin converter? 8 AOs per band seems a bit of an overkill.</p>
Hey, really awesome job on this, I've been working on figuring out how to build a Nixie graphic EQ myself and this has definitely given me some guidance. For the log to linear conversion I was looking at a slightly different approach though. I would be curious of your thoughts on using the anti-log converter discussed in this paper as opposed to your method. Only concern is it doesn't discuss a &quot;fast anti-log converter,&quot; which would be needed since the normal one would be too slow. I'm hoping I'll be able to derive it based on the other circuits in the paper though. http://s.eeweb.com/articles/2010/12/16/Log-Converters-1292533187.pdf
<p>Hi Eric, did you succeed in creating a log converter out of that whitepaper? Could you please share the schematic? </p>
<p>Oh very nice. this project inspired me to make my own variation. Altough that one would be partly Digital.</p><p>Im working on a small scale version that uses a ATMega, a MSGEQ7 Spectrum analyzer IC and a simple 8-channel DAC IC(TLC series). The output voltage is converted to a controlled current by aid of a High-voltage Transistor. Right now im experimenting with a Fast-Hartley-Transform which suprisingly can work at a decent speed on a lowly ATMega if willing to work with less accurate reading(8-bit). Need to filter the signal a bit though.</p><p>Anyway thanks for the inspiration! ^^</p>
<p>This is kool. I want to make it for my college project. I do have a question though. if I build the entire circuit in full but I only use lest say 10 tubes total, would the extra channels simply not be displayed, or would this be detrimental to the rest of the circuit. I only ask because I want to build the full circuit, but I don't have the money for so many tubes.</p>
<p>I haven't made this one myself yet, but I'm willing to bet you would need to expand the band-pass filters to cover the parts of the spectrum that you are missing. You wouldn't want to leave out the upper or lower bands, but you could &quot;stretch&quot; all of the bands so that 5 tubes per channel would cover the same 20 - 20000 Hz range that 7 tubes cover in this guide. You might want to look into a lower Q factor for the filters. </p>
Where can I get the shopping list?
Very nice! Did you use EAGLE for drawing the schematic? :)
This is really terrific. I love seeing nixie-based projects!
Thank you for the great instructable, very detailed. I was especially excited to see the filter for different frequencies as I have been looking for a good low-cost design to build
Dude if u could hook that up in your car that would be tight!
I am very interested in building a project like this, the parts list says 170 (One Hundred and seventy) 10k resistors are used, is that a typo or are there really that many 10k resistors used? If i were to build a one channel visualizer, would i take this parts list and divide it by half (other than the parts where only 1 is used of course)?<br>
I would like to make one of these for my&nbsp; <strong><a href="http://www.melbournedjhire.net/">Melbourne DJ hire</a></strong> company. What would the total cost be?
basses should be on the left side but you have it reversed on the left EQ is it on purpose?
Yep, symmetry is pretty
Is there any way to add a couple more frequency bands? I have a 10 Band Stereo EQ that this would go nice with in a custom box. Does this use converted AC voltage or just a battery?<br>
This is incredible, what was the total cost of this project for you?
Wow! That's really impressive, especially for someone so close to my age! You should really consider going to MIT or CalTech. So anyhow, what made you want to use nixie tubes?<br><br>Oh, and I was wondering a couple things. Could you use, say, five LEDs instead of the tubes and make it small enough to fit in a pair of headphones (I could always add a bit to the sides, bottoms, or even the chord itself)? I was thinking of making a headset mod with a circular visualizer on the side. Any ideas? Thanks in advance! And good luck in the future!
i would love to have this also! or maybe something with a microphone so you could take it anywhere and have it listen to anything!
Great Instructable, especially for a Freshman. I wish I knew electronics that well.
Very nice indeed. When I was an Electronic Technician in the US Navy (early 1970's), one of my favorite pieces of equipment was a frequency analizer with a nixie tube read out. I'm glad to see nixie tubes making a comeback in a lot of projects.
Very nice! I'm jealous that I never made anything quite that impressive when I was at school in electronics! My final A2 project was a greenhouse climate control system. Never used that dot matrix board but it seems to be a nice compact solution. We had PCB manufacturing facilities at school so I was lucky enough to be able to make my PCBs there. If anyone is interested in the Design, Development and Manufacture of a PCB follow this link to a series of video that I made: http://bit.ly/iNr6Z4
Would it be possible to make one with more tubes? I am looking into building a 4' visualizer to mount to the front of my keyboard stand. Thanks.
Of course, this is pretty scalable. A while back I was working on making this modular, having each tube attached to the side of a long, narrow PCB, and they could be stacked.<br>The only things you need to add more is more power, and redesign the filters to cover the audio range better. In other words, you need math.<br><br>http://www.youtube.com/watch?v=x0NJhbx9IYM<br>This guy did something similar, but he went digital with it (FFT) and has some crazy power boards.
i put it in my xbox hacking lol the audio from my xbox to go on the cover it looks so cool thanks :)
ohh post a pic
Ok i am building a bass guitar right now and was thinking 2 of those nixies would be perfect on either side of the 4 strings, so if anybody is interested in some 1 on 1 chatting about how this could be done i would really appreciate it<br>
First of all, this is a very complex project for a junior in high school to accomplish. so bravo on that. (I barely had my soldering skills and basic circuits at that age) . Really a unique and amazing build. This would look really good with a more modern enclosure and of course with the right music.
Wow, man! This is gorgeous! This instructable got me into both Nixies and Honeycut!
Its awesome... just im wondering where can i find those tubes, can it be bit simpler and&nbsp; can it work with microphone?<br />
Hi there! Could I use a more common LM339 voltage comparator instead of the ts3704 which is giving me a hard time to find?<br />
You would need to adjust the section in between the comparators and the display op amp. &nbsp;The TS3704 has push-pull outputs, which considerably simplifies things. &nbsp;The LM339 has pullup resistors on the outputs, which makes it impossible to just attach all of the outputs with resistors to average them.
<p>I have been looking for exactly this for a different project i am working, my only problem is that i need a variable voltage between 0 and 5 volts instead of your 12v current system. Can anybody here help me in acheiving this. Its a bit over my head, so i would really appreciate some help.</p>
Great project! I've ordered most of the same parts. What are the voltage requirements for the capacitors? You wouldn't happen to still have the parts list from mouser and digikey?<br />
Based on a comment you made before, is the information below correct?<br /> <br /> 14x&nbsp;&nbsp;&nbsp; 100uF electrolytic polarized capacitor 25v<br /> 14x&nbsp;&nbsp;&nbsp; 4.7uF electrolytic polarized capacitor 25v<br /> 18x&nbsp;&nbsp;&nbsp; 1uF capacitor 25v<br /> Are the below capacitors multilayer ceramic, or<font size="4"> </font>mica? Would ceramic suffice (I didn't see polarity noted for any of them)? <br /> <br /> 13x&nbsp;&nbsp;&nbsp; .1uF capacitor (should this be 14?)<br /> 8x&nbsp;&nbsp;&nbsp; .01uF capacitor<br /> 4x&nbsp;&nbsp;&nbsp; 1000pF capacitor<br />
I love it!<br /> <br /> Thank you for writing and shareing this project. :)<br /> <br /> <br />
Does the value of Cin matter ?
The image annotations are a bit buggy, it should indicate that Cin isn't needed in this design, I didn't include it in the final schematic or board.
You can probably use half the parts if you use LM3196 chips for the log to linear, they are identical to the circuit that is printed on the original post but cut it from 4 chips to 1 on each tube. I've got a set of IN9 tubes that I'll be building this with. But I'm having a hard time understanding the frequency splitters, how do you work out what resistors to use for each frequency?
can i use 9 in tubes in sted of 14in X 13in