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--- en:projects:nixie-clock:start [2011/02/19 13:51]
alex
+++ en:projects:nixie-clock:start [2011/06/04 11:09]
alex [Specifications]
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 ====== 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}}
-{{:nixieclock-1.jpg?600&direct|}}
 ===== 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 a 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 a detailed introduction, please 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
+    * 4.7µF Inductor