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Topic: Open Source Nixie Clock! (Read 10737 times) previous topic - next topic

Open Source Nixie Clock!

Hi All,

Several weeks ago I won one of the three Cadsoft Eagle "Hobbyist" licenses given away by DP! Thanks to DP, and especially to Cadsoft, for their support and generosity!

I won the license based on my desire to design an Open Source Nixie Clock, and I plan to share that design here in the DP "Project Logs" forum! I've been working on this design for a couple of months, but was forced to put it on the shelf due to the board size limitations imposed by the "free" version of Eagle. With the free version, my "tube board" design would only allow space for 3 of the 6 tubes I intended to use!

Over the next week or so I'll be posting the preliminary schematics, parts lists and board files for the design. I'll also be discussing the overall structure and design of the firmware. My intention is to make an initial prototype using the 'DorkbotPDX' PCB service, and then have the final boards make at Seeed. I'll probably get extra boards, so anyone that needs one will not have to order their own, but can get one from me. The firmware for this project will be written in 'C' using the CCS 'C' compiler, although the code should be fairly transportable to other compilers. I do plan to leverage a lot of the hardware design, and firmware from my recent GLCD clock project covered here earlier.

My design will be based on the 'IN-14' Nixie tube. These tubes are an excellent size for clocks, and can be readily purchased from sources on eBay for about $7 USD per tube. The design will feature six of these tubes, and two neon "colon" digit separators.  The design will feature separate 'clock' and 'tube' boards, so other tubes can easily be supported!

Nixie Clock Design Features

(6) IN-14 Nixie Tubes
18F2550 Microcontroller with USB
+12V DC Input (Wall Wart)
Maxim DS-3234 RTC with TCXO
Battery Backup
Time Setting via USB or On-board Switches
Power Down Mode (Increase Tube Longevity)
Anti-Cathode Poisoning Mode (Increase Tube Longevity)

I've designed a hardwood base for Nixie Clock I've got in mind, and I've selected an acrylic display case to go over it. Once complete, this clock should have a very 'professional' look and should be worthy of display in a prominent location in your home!

If anyone else would like to help, or has some other ideas for design features, please feel free to chime in!

Stay tuned!!

John

Re: Open Source Nixie Clock!

Reply #1
Hi, cool project. May a make suggestion.. try using a newer PIC for your project..
the reason I sugest this is that with new pic with integrated PWMs, DACs, and comparators you could implement the HV power supply on the PIC...it could help reduce the cost of the design.
here is an app note we wrote about that explains how to implement it..
http://dangerousprototypes.com/2011/12/18/app-note/
best regards FIlip.


Re: Open Source Nixie Clock!

Reply #3
I am thinking of designing a simple multi protocol Nixie tube driver.
It would have a PIC12F1822 to handle the protocol conversion to Seral, and a HV power-supply. I am thinking of making it as a module that anyone could use to provide HV for Nixies and drive shift registers with transistor arrays for the digit displays.
best regards FIlip.

Re: Open Source Nixie Clock!

Reply #4
Hi All,

Thanks for the suggestions! I will definitely take a look at some of the more modern USB-capable PICs! I've used the 18F2550 in a number of projects already, so it's my "go to" device for USB applications. Doesn't mean that there aren't other, better, choices though.....

I'm planning on using the MAX1771 High Efficiency DC Step-Up controller in my design to generate the high voltage required for the Nixie tubes. I want the "sub-circuits" of this design to be as portable as possible, so that one is not locked into a specific processor. I think the dedicated HV power supply meets that goal without incurring a significant additional expense!

I also wanted to mention that I'm leaning toward a fully through-hole design for my Nixie Clock in order to allow as many people as possible to participate! 

Thanks,

John

Re: Open Source Nixie Clock!

Reply #5
[quote author="tayken"]Also you might want to check out Ladyada's tutorial, it has a nice calculator.
http://www.ladyada.net/library/diyboostcalc.html[/quote]

Nice find on the calculator! I am planning on playing around with smps's using pic's when I finish making my PCB thing, so this will be an awesome resource.

Also, good call on doing through hole. I presume the nixie is 150v+ so SMD would be a bit problematic at such voltages, but with through hole you can have easier/better isolation.

Re: Open Source Nixie Clock!

Reply #6
Hi All,

I have just about completed the first version of my open source Nixie Clock circuit, and I'll be posting the schematic in the next couple of days. In the meantime, I thought I'd show off the contents of a package I received from the Ukraine just before New Years containing my Nixie Tubes, neon bulbs (for colon separators), and high voltage driver IC's. With these items in hand, the pace of this project will surely speed up now!!

[attachment=0]

The Nixie Tubes are Russian IN-14 tubes that stand about 2" (50mm) tall. These tubes have a nice rubber base, and long solder leads for attachment to the PCB. The neon bulbs will be used as the 'colon separators" between groups of digit to create the familiar '12:59:59' clock display format. The K155ID1 high voltage driver IC's are BDC-to-Decimal display drivers with open collector outputs capable of withstanding the 180VDC required to fire the Nixie tubes. These IC's will make driving the tubes infinitely easier!

Stay tuned!

John

Re: Open Source Nixie Clock!

Reply #7
Nice, a nixie clock was my first major microcontroller project. Let's hope the Russians never run out of antique electronic junk to sell us, or engineering may die out completely :)
Got a question? Please ask in the forum for the fastest answers.

Re: Open Source Nixie Clock!

Reply #8
Hi Ian,

Yeah, isn't that the truth! There is some pretty wild stuff available from the old Soviet Union, and it's fun to work with! Lately, Nixie tubes seem to have had a new resurgence in popularity with the 'retro' crowd as their prices have been climbing steadily. My favorite Nixie tube is the IN-18, a nice, big Nixie, but the price of those bad boys is now up to about $60 USD per tube!!

John

Re: Open Source Nixie Clock!

Reply #9
Did this awesome project ever finish?
Was really hoping to get a glimpse of the schematic and information relating to this project.

Thanks!

Re: Open Source Nixie Clock!

Reply #10
Hi,

Sorry for the late reply as I haven't visited in a while, and only did so recently to post another project!

The Nixie clock project was completed to the working prototype stage. There were a couple of issues with the original PCB's that need to be taken care of, and I need to wrap up the documentation. I'm planning a build of 5 clocks for Christmas presents, so I'm getting back to this project very soon!

Thanks,

John

Re: Open Source Nixie Clock!

Reply #11
Hi All,

For anyone that's interested, here is a picture of my Nixie Clock prototype! I had the hardwood base made out of Maple by a local cabinet shop for $30, and the Acrylic cover was sourced from a company that specializes in display cases for about $15. The clock is working extremely well, and really looks nice, especially in low light conditions!

[attachment=0]

Since the original concept, I've made a number of circuit changes based on the performance of the prototype. Most significantly, I've eliminated the USB interface, as the DS3231 RTC has such low drift that it wasn't worth the effort! The pushbutton time/date setting feature is not bad, and I plan to add an Xbee or Nordic receiver to the final design for periodic remote time updates via GPS.

There are a number of board issues with the current design (which thankfully cannot be seen!) that will require some modifications. It's minor stuff, and I plan to get to it as soon as I finish the 'GPS-to-Xbee' bridge project I'm wrapping up now that will allow automatic synchronization of the Nixie clock to GPS time. I'll post a description of this project shortly!

I need to keep moving on this project, as Christmas is fast approaching! Sigh! So many projects, so little time!!

John

Re: Open Source Nixie Clock!

Reply #12
Very nice work, now you just need to make all the fancy chip circuitry into nice glowing Valves and it will be even better ;)

Re: Open Source Nixie Clock!

Reply #13
Cool Clock !  I also have an open-source design nixie driver board. All CAD and source code available off this page:
http://http://cogwheelcircuitworks.com/projects/nixie-system/nixie-driver-board/nixie-driver-board-rev-b/
(I've been busy with another business venture which required me to purchase a pick and place machine, and I plan to put these boards back in production soon)
Cheers !
..c