Nixie Tube Power Supply

Sphere's Nixie Tube Page specifies that the IN-14 tubes require a 170-180VDC power supply and a 33kOhm resistor in series (before the anode). Most AC to DC power supplies provide between 3.3VDC to 15-20VDC. I also want to have 5VDC for logic circuits. For the first nixie clock (Nixie 1.0), I purchased a boost converter kit, something like this one. For me, it was a "black box" when I soldered the components on, but I knew I needed to figure out a bit more about how it works if I intended on making my own from scratch.

I manually copied the circuit diagram into Eagle Cadsoft (you can get a limited version for free which should work great for this project from here). Below is a picture of the circuit diagram I drew up. If you need help with using Eagle (...and you probably will because it is not intuitive), take a look at some youtube videos. There are comprehensive tutorials out there... that's the way I learned how to use it.

So, this schematic looks daunting, and to tell you the truth, I'm not completely certain what every part does, but I will try my best to explain what I do know. Some of my information came from this helpful website.

I have +9VDC coming in up top. The C1 capacitor is there to smooth out the DC input in case there is any ripple. This may not be necessary, but it can't hurt. A point of warning, make sure that all of the capacitors are rated for the appropriate voltage.

The inductor (L1) is the business end of things and is hooked up at one end directly to the 9VDC and the other to a miriad of other components. The purpose of the other components is to switch on and off the flow of current in order to maintain a high potential (160-200VDC). After the diode (D1), we have 160-200VDC. So what are all of the other components?

The C3 and C4 capacitors are high-voltage capacitors which are there to buffer the output voltage. The integrated circuit (IC) is a 555 timer. The 555 timer is there to rapidly switch the transistor (Q1) on and off. When the transistor is closed (passes current), the inducted current goes to ground. Once switched open, the current is forced to pass through the diode. If this process is repeated at a rate which is faster than the decay time of the current running through the inductor, you get a potential build-up passed the diode. I will talk a bit more about how the 555 timer works in general later, but right now you have to believe me that many of the remaining components are just there to ensure the switching is rapid.

Lastly, the voltage has to be regulated, or the voltage will keep rising to no end. This is done using the resistors R3, R4, and R5. R4 is adjustable, so you can adjust the final voltage. This resistor series acts as a voltage divider, allowing the transistor (T1) to begin conducting once we reach 160-200V. Once T1 conducts, the voltage is dropped, and increases the frequency of the 555 timer cycle, providing active feedback.

Now that I know how this works, I can begin soldering! See you next time.

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The Plan

Ok, so Nixie 2.0 needs to be different from all of the other nixie clocks out there. I'm tired of seeing the same thing all the time. People make neat boxes and enclosures, but they sometimes lack that coolness factor.

After thinking about it for a while, I thought it would be neat to have modular units for the tens hours, hours, tens minutes, and minutes. I admit, I'm getting this idea from a ThinkGeek product, but I don't think the final product will look anything like their Matrix Cube clock. I made a simple sketch, which is shown below:

Yeah, it's crude, but I hope you get the general idea. There will be a base which contains all of the business-end things--the power supply, timer circuits, and buttons. Each of the nixie tubes will be contained in a very small box which will be wired to the base. All of the boxes for each of the tubes will be able to nest into a depression in the base, or they can be moved around at will. I wonder if I need to put something heavy at the bottom to make sure they don't tip over. I have thought about maybe even using a monitor cable as the method of supplying the wires to the tubes, allowing me to unplug each nixie tube box if I want to exchange it, or it may allow me to put the nixie tubes in confined areas, hiding the base.

The point here is that I want the base to be as skinny as possible, so I will try to compact all of the components into as small of an area as possible. I really have no idea about the location of the buttons, the style and material of the box, or how I might add the neon lamps. All I know now is that I need to make as small of a power supply as possible, on the cheap, from scratch.

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Nixie Tubes!

Nixie Clock 2.0 has some pretty neat inspiration -- a plethora of nixie tubes. My older brother gave me a bunch of Russian IN-14 tubes. Take a look at this website, they have an insane number of tubes for sale. He got them on ebay still attached to a display rack:

Of course, I have already taken a few of them off of the rack (desoldering these was quite a chore). You can see on the far right that they come with a few neon lamps, which might be good for the colon between hours and minutes? All of these items take 170VDC and each of the nixie tubes has an anode and 12 cathodes (one for each of the digits, 0-9, and the last two are for decimals before or after the digits).

So, I think you can probably already get an idea of the issues associated with making a clock out of these tubes. They take very high voltage (although very low current) and require switching between each cathode in order to display any one of the digits. I also need 5V for switching using integrated circuits. I would like all of this to be in a compact design. Speaking of design... next post. See you then!

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Nixie Clock 2.0

So, it's time to make a nixie clock! To those who don't know what nixie tubes are, take a look at the wikipedia page: http://en.wikipedia.org/wiki/Nixie_tube. My older brother gave me a bunch of these over the past year. They come in a number of types and sizes, but they all have a similar orange-red glow to them. They were used as an early display technology, but now people mostly use them for making retro displays such as clocks.

I have already made a nixie clock. A picture of the clock is shown below (thanks Lance for taking the B&W film picture of me). I learned a great deal about electronics from the project, but I used an Arduino (user-friendly programmable input/output device) for the project and purchased a kit for the power source. It does have a lot of features, like two alarms, temperature reading (shown below in degrees celsius), 12-hour/24-hour format, sleep setting (where it turns the tubes off at night), and an auxiliary input which does nothing right now. Still, I wanted to do everything from scratch and not rely on convenient technology.

So, this blog will now be dedicated to updating the progress of making the nixie tube clock completely from scratch, but without the fancy extras. I will start with a 9VDC power supply and make all of the components from either available or purchased resistors, integrated circuits, capacitors, transistors, etc. The next post will explain what my design will be and I will follow with updates on everything from the power supply to controlling the tubes and constructing the actual clock.

I might also show how I made the first nixie clock (Nixie 1.0). I'm pretty proud of it.

Enjoy!

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