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en:projects:nixie-clock:start [2011/02/19 13:51]
en:projects:nixie-clock:start [2011/06/04 11:11] (current)
alex [Specifications]
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 ====== Nixie Clock ====== ====== Nixie Clock ======
-I designed and built this nixie tube clock in my senior year of high school. ​ It's a basic 4 tube design controlled by a Microchip PIC microcontroller. ​  +{{:​nixieclock-1.jpg?​380|Nixie Clock}}
- +
 ===== Introduction ===== ===== Introduction =====
-In my senior year of high school, the [[http://​www.nutsvolts.com/​index.php?/​magazine/​issue/​2006/​10|October 2006]] issue of [[http://​www.nutsvolts.com/​|Nuts and Volts]] featured an article about a Nixie tube clock.  ​The [[http://​www.nutsvolts.com/​index.php?/​magazine/​issue/​2006/​09|previous issue]] had discussed a high voltage power supply built around a PIC microcontroller. ​ I had been experimenting with PIC microcontrollers for quite some time before and I was intrigued by the prospect of using a PIC microcontroller to generate a rather high voltage from a logic-level supply. ​ I didn't have much use for it, though. ​ After seeing the Nixie clock article, I now had the perfect application for it.  So, I bought several tubes off of ebay, direct from the Ukraine, and got to work. +I designed and built this basic 4 tube nixie clock in my senior year of high school.  ​
- +
-The most important part of the clock is the nixie tube.  I wanted to make a clock with a low part count and a small physical size, so I settled on a four tube clock. ​ I did some research online to determine the most optimal drive configuration for the least complexity hardware-wise. ​ Many designs biased the anodes directly and then used either ten transistors and a demultiplexer chip or a special high-voltage demux chip per tube.  I definitely liked the hv demux chip idea because it means I need one part instead of 21 (demux + 10 transistors + 10 bias resistors). ​ Another site that I looked at added anode-side switching and then used only one driver chip.  I really liked this idea, primarily because the driver chips are expensive and, just like the tubes, I had to order them directly from the Ukraine. Replacing three driver chips with eight transistors and eight bias resistors seemed like a fair trade.+
-Then I had to figure out how to do the other thing the clock will have to do well -- keep track of time.  I settled on Maxim/​Dallas part, the [[http://​www.maxim-ic.com/​quick_view2.cfm/​qv_pk/​3914|DS1340C]], with an I²C interface and a built-in crystal, further reducing the parts count.+For more detailed introductionplease read the [[history]] page.
-In researching how I would build my clock, I looked at many pictures online of other clocks. ​ Some were completely over-the-top,​ some were too simple. ​ I wanted a sleek, modern looking clock that isn't too difficult to build. ​ One of the ideas I liked about one of the completely over-the-top clocks is blue lights underneath the tubes. ​ The little hole in the bottom of the spacer on the bottom of the tubes that I bought happens to be just the right size for a 3mm LED.  So I bought a bunch of 3mm blue LEDs off of ebay.+===== Detailed Information =====
-For the case, I decided on a simple design based on acrylic. ​ The top and bottom would be black acrylic and the sides would be made of clear acrylic.+  * [[History]] 
 +  * [[Power supply]]
-I decided to write the firmware for the clock in C in [[http://​www.mikroe.com/​|mikroElektronika]]'​s [[http://​www.mikroe.com/​en/​compilers/​mikroc/​pro/​pic/​|mikroC]] development environment;​ I had bought it along with an EasyPIC4 development board from them some time before.+===== Specifications =====
-The result of a pile of work spread out over several months is shown above. ​ +  * Display 
 +    * 4x ИН-16 (IN-16) Nixie tubes 
 +    * 208V anode bias 
 +    * 1x К155ИД1 (K155ID1) high voltage BCD to decimal decoder/​nixie tube driver (74141 equivalent) 
 +  * Processor 
 +    * Microchip PIC18F2550-I/​SO 
 +    * 20 MHz clock, 5 MIPS 
 +    * 32K Flash 
 +    * 2K RAM 
 +    * 10x 10-bit ADC 
 +    * I²C, SPI, and EUSART peripherals 
 +  * Clock 
 +    * Maxim/​Dallas DS1340C 
 +    * I²C Interface 
 +    * Built-in crystal 
 +    * Backup battery support 
 +  * Power Supply 
 +    * Input: 12V DC 
 +    * Output: 5V DC 
 +    * 7805 regulator 
 +  * High Voltage Power Supply 
 +    * Input: 12V DC 
 +    * Output: 12V - 300V DC variable 
 +    * Boost topology 
 +    * IRF720 400V 3.3A N-channel MOSFET 
 +    * HER105 400V 1A fast recovery rectifier 
 +    * 4.7µH Inductor