My type 1a Nixie clocks have the following general features:
The first clock of this type I built has the following specific features:
- One-digit display, showing the time and/or date sequentially with a user-settable duration per digit and for the gaps between digits. A brief gap is needed in order to make times with repeated digits (such as 11:12:22) readable, although the gap time can be reduced to zero if the user really wants to.
- Timekeeping based on the 60 Hz powerline frequency (which has extremely good long-term accuracy), plus a backup capacitor to keep the clock running at reduced accuracy during a power failure. The date and all display options are stored in EEPROM, so that generally only the time will have to be reset even if backup power is exhausted.
- Datekeeping is fully Y2K compliant, and is valid through the year 9999.
- Three-button user interface - a SET button which steps through the settable values, and UP/DOWN buttons (which may actually be different directions on a momentary toggle or rocker switch) to increment or decrement the selected value. Pressing UP and DOWN simultaneously (if possible on a given clock) increments the value by 20. When not in set mode, UP and DOWN momentarily produce an alternate display - for example, they can be configured to display the date if that isn't part of the normal display.
- Currently based on a PIC16F84A processor (will probably switch to the 16F628 once my current stock runs out). 491 out of 1024 words of program EEPROM are used, and about 42 bytes of RAM.
- Uses a calculator-style Nixie tube with 0.5" digit height.
- Housed in an AC adapter case, designed to be plugged directly into an AC outlet. Dimensions are approximately 2" wide, 2 5/8" high (3 1/4" including the switch handle), and 1 3/4" deep (2 3/8" including the prongs).
- The SET button is a magnetic reed switch at the lower front of the case, to prevent accidental changes to the time. The UP/DOWN features are done by pushing a momentary toggle switch on top of the clock to the right or left.
Click here for a copy of the instructions for setting the clock, in Acrobat PDF format.
Click here for some pictures of the circuitry inside the #1 clock.
My second clock of this type is about as different as can be, yet uses basically the same design. It is based on a Burroughs Beam-X decimal counter module, although the Beam-X tube is not actually used by the clock.
Click here for the auction description of the #2 clock, including an animated mockup.
Click here for interior pictures and technical details.