The Cogwheel Nixie Tube Clock                     last updated: 8APR008

Bluetooth-Enabled B7971 Clock

Here is a 7 tube B7971 nixie display utilizing a Bluetooth module to communicate with a PC. Such a large tube display is most versatile when placed under PC control; In addition to time synchronization, any type of real-time information can be displayed. While my driver board is already equipped with an RS232 port which could be hard-wired to a PC (or GPS module), the large tube display is best placed some distance from the viewer, making a hard-wired connection back to the PC unsightly and inconvenient.

I researched dedicated RF modules but they had the disadvantage of requiring a matching module on the PC side. Most people already own Bluetooth-enabled PCs.

Above is a picture of the whole display. It is powered by a wall-wart. There are 3 boards; The driver board, a 3 tube display board, and a 4 tube display board. I will probably lay out a 7 tube board. The driver board can drive a maximum of 7 tubes.

I chose the  Roving Networks  RN41 Bluetooth 'modem' module. It is very easy to use; It appears as a COM port on your PC so software so any software that can communicate with a COM port can be used to drive the display.

Below is a close-up of the module; This version of my driver board had to be modified to accept it. The next version will have a spot laid out so there will be no jumpers and cuts necessary.

More general info about the driver board:

(BTW, you might also like the Cogwheel Nixie ScreenSaver)

The Cogwheel model 301x  is a versatile Nixie tube clock driver board. Its features include:

• Drives tubes located on a separate board to accommodate a variety of tubes and custom enclosures. 
• Drive capability for up to 7 tubes with up to 14 cathodes each; 
• Supports classic “0 through 9” numeric tubes as well as large segmented alpha-numeric tubes such as the B7971. 
• Symbolic tubes and individual neon lights can also be driven. 
• Stable, modern design utilizing surface-mount components.

On board features include:

• Flash-upgradeable processor (Microchip PIC16F877)
• Non-volatile configuration memory
• Adjustable high voltage generator fully controllable by processor.
• Non-volatile clock chip (Dallas/Maxim DS1302) with capacitor backup for maintaining time for up to 12 hours across power outages.
• RS232 Serial Interface – Can be interfaced to a GPS receiver, personal computer, or other device.
• 1 pps (pulse per second) TTL level input for incrementing time from external source (GPS receiver or other equipment).
• Cool-running 5 volt switching power regulator – Can supply up to 500ma of power to an external device such as a GPS receiver.
• Infra-red receiver interfaced to a secondary processor (Microchip PIC12F675) for control
• AC powerline frequency can be sampled by processor Runs on AC(9-12V) or DC(12-15V) power

Latest software release features include:

• Complete Hours, Minutes, Seconds, Year, Month, Day timekeeping
• Configuration via buttons, infra-red remote, or serial command interface
• Configurable synchronization source - Non-volatile real-time clock, GPS, or serial
• Configurable time increment source – Internal, 50/60 Hz AC Power, or 1 PPS input
• Optional Daylight Saving Time Correction (North American rules)
• Per-digit transition fading effect
•  Smooth transition between HHMMSS and YYMMDD displays
•  GPS – Display blinks if GPS does not have a fix
•  GMT offset to convert GPS time to local time

Watch ebay and yahoo group neonixie-l for Cogwheel Clocks in limited edition cases

Documentation  Nixie3018UserManPre2.pdf   Implementation: MCU: Microchip PIC16F877A Programming Language: C High Voltage Generation: switched mosfet/inductor driven by pwm output of MCU Cathode Drivers: Zetex FMMTA42 HV switching transistors Anode Drivers: Toshiba TLP127 Optoisolators
DRIVING 8422s	DRIVING IN18s	DRIVING 7971s