Nixie Tube Clock Project

A couple of months ago I got my hands on some Nixie Valves/Tubes, I’ve now finally got around to doing something with them. The plan is to reinvent the wheel an make a clock with them, but in the long run I want to put an LCD screen bellow the nixies  that shows tweets from the people I follow on Twitter, as well as maybe some other info such as the weather.

To do this I’m using an Arduino variant made by the London Hackerspace called Nanode, this is very similar to the standard Arduino except that it includes an Ethernet port for network communication. Having this Ethernet port will allow me to not only pull tweets from Twitter, but also sync the time so that the clock will always be correct!

So what have I made so far? I’ve put on a breadboard the basic setup for the clock part. The plan is to have 4 nixies multiplexed with a single Chip using Optical Isolators. The chip I am using is an old Russian km115, This allows me to cycles through the different cathodes on  the nixies by only using 4 pins on the Nanode, Think BCD.

I currently have the the chip placed in the breadboard with a single nixie connected. Four LEDs  are in place which will be replaced by the optical isolators for the Multiplex. For now I’m just having the Nanode cycle through the different digits with a small delay.  The nanode is going to handle all the work in terms of deciding which nixie should show what number, keeping the time, the twitter connection, etc..  To power the nixies I’m using a 9v battery connected to a power module made by Kosbo. This power module outputs about 189 Volts, I’ve also got a 5k6 resistor in series with the the nixie to limit the current being pulled (The nixie’s limit is < 3.5 mA.)  obviously with such a voltage I need to be a bit careful to make sure it doesn’t get anywhere near the nanode, hence  why I’m going to use optical-isolators. Though let’s just say with 180ish volts I have had some shocking good fun with this module. I think I’ve  managed to shock myself about 3 or 4 times now!

I’ve started work on the code for the nanode, at the moment it just cycles through the numbers 0 to 9, and through the different LEDs (defined as opto in the code). I’ve posted the code in pastebin, viewable  here .

Obviously not very much to it yet I have a long way to go. The next step is for me to work out how to use the Nanode’s Ethernet port as well as decide how the clock is going to look. I do have a piece of clear plastic which I’m thinking of embedding the nixies into, but I’m still working out the specifics.

Thanks goes to Matt Lloyd from Nottinghack who’s helped me out a great deal with this.

 

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