This nixie clock was designed by Dave Thorpe, and built from a kit available from his UK based Unusual Electronics website. Dave has done a fantastic job with this design and his software has many unique features. The clock is extremely configurable, with over thirty options to customise the look and behaviour - (see the features list below). I especially like the scrolling date, and other digit cycling effects, which look great. This clock is anything but dull, and a real pleasure to watch!

• Unusual Clock User manual.pdf

Front view of the finished clock

In more detail
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	The finished PCB. The high voltage generator is handled by the processor, reducing component count. 74141 type decoder chips are used to drive the Nixies, which are configured in a 3*2 Multiplex matrix.
	Precision laser cut, and highly polished, stainless steel plates are used for the case. They sandwich together with the PCB in the middle, and look great. The sides are a piece of thin, perforated stainless steel (3mm perforations).
	Here the PCB has been mounted to the top plate, and the DCF77 connector attached. D5 thru D10 are the blue LED's which lookup the Nixie's base.
	Great care must be taken when mounting the Nixies to get them straight, its impossible to move them (without breaking the glass) when all the pins are soldered!
	The set switches and light sensor can be seen. Normally, the red and green LED's flash at 1 second intervals, in the case of a HV fault, the flash sequence indicates the possible cause.
	Power is plugged in (left). The two buttons are for setting the clock and/or options, below them is the light sensor which can automatically dim (or turn off) the Nixies in the dark.
	The blue LED's look great, and can also be seen from below the top plate. Numerous software options exist to alter the display characterisitcs.

A top view of the finished clock
There's nothing like polished stainless steel, just be careful with those finger prints! The underside of the blue tube leds reflect inside the case and glow through the perforations in the dark.

Nixie Clock Features

• Microchip PIC16F876A 8-bit CMOS microcontroller ic.
• Six large IN-14 Nixie tubes with 19mm (3/4") high digits.
• The nixie tubes are driven in a 2*3 line multiplex which provides fast display refresh, lower driver chip count and reduced power consumption.
• Normal clock timing is provided by the cpu crystal which can be finely adjusted and stored using the pushbuttons.
• The clock can optionally derive timing from the 50 or 60Hz mains frequency (provided an AC power adaptor is used).
• Accepts MSF (UK), DCF77 (Europe) or GPS time receivers for accurate time and date.
• Can be interfaced to a Windows 98 or XP computer serial port to synchronise with the PC time
• The time can increment under the control of an external 1pps time pulse.
• The high voltage supply is controlled and regulated directly by the microcontroller using PCM.
• The clock is fully configurable with over 30 main options with many setting choices - configurations are retained in memory.
• All clock option settings are easily adjusted using just two pushbuttons.
• Digit cross-fading effects (5 levels) - blends digits as they change.
• Scrolling date effects - 4 options for scrolling the date plus a random effect selection option.
• Manually controlled display brightness selection (5 levels).
• Time controlled display dimming and/or turn-off.
• Light level controlled display dimming and/or turn-off to increase tube life.
• Digit cycling effects - 8 different effects plus a random selection option. The cycling effect speed and run intervals are configurable.
• A special long cycle effect can be set to run at midnight - to help prevent Nixie "cathode poisoning".
• 12/24 hour time modes with leading zero blanking options.
• Date display in UK/US or International format with display interval and duration configurable.
• Automatic leap year adjustment.
• The clock can offset the time received from MSF/DCF77, GPS or WWVB sources by up to +/- 14 hours.
• Six bright tube illumination LEDS can dim along with the nixies, or be continually on/off.
• Dimmable neons for colon display - these can be set on/off/flashing (two speeds) or indicate AM/PM.
• A (decimal point) type nixie AM/PM indicator which is configurable and dims with the display.
• One button can be reconfigured from it's default dimming function to switch between 12/24 hour time, show the date,toggle cross-fading or switch to a completely different whole clock configuration for personal preferences.
• There is a user re-settable tube hours usage counter.
• Two status LEDs provide an indication of normal clock activity, external time pulses and any errors. These can be switched-off when not required.
• PCB dimensions: 150mm x 60mm and 20mm underside clearance. (5.9in X 2.4in X (0.79in)