Home Page . . . . . . . Email: . . . . . . . . neelandan-at-gmãil·çöm
The design of this clock was inspired by a certain stellar pursuer, who wrote to me saying he wanted something better than the pretty basic things available on the web.
Confused about nixies, are you? Read the F A Q .
Want more electronic circuits?
See my Circuits page.
Want an easy project to start with? Try the Nixie Spinner.
Neelandan's Nixie Clock is designed around cascaded 4017 CMOS I.C. counters with transistors driving the nixies. This is in contrast to designs using a programmed microcontroller. The microcontroller version is able to offer a large number of features with minimal circuitry. However, the constructor is stuck with the features programmed into the microcontroller. The average nixie clock builder will not have the necessary skill or equipment to hack the program to install a customised feature.
The seconds pulse is derived from a quartz analogue clock with sweep second hand, the one that jumps every second. The mains frequency is not stable enough in my part of the world. Getting a quartz crystal oscillator to work is, in my opinion, a too fiddly piece of work. The quartz analogue movement is available everywhere and easy to adapt as a source of seconds pulses.
CMOS IC counters are used in groups of two, dividing by sixty to get minutes, by sixty again to get hours, by twentyfour to get days and then one single stage of division by seven to get day of week.
The 24 hour count is translated using an EPROM to the 12 hour - am/pm format or to the 24 hour format for display. Those who have tried it will know the difficulty of reconfiguring a counter to switch between 12 hour and 24 hour modes - without losing count. Too difficult to do except in software, and that involves using a microcontroller such as a PIC.
Chimes at quarter hour intervals and hourly signals are decoded from the minutes counter. I am thinking of hacking a walkman type cassette player to play a loop of tape to generate those signals. The necessary modifications will involve adding reflective stripes to the tape to indicate end of signal and the necessary electronics to make that work.
Alarm time is decoded by rotary switches and fed to a raucous sound generator. I like the feel of turning switches to set the time. Using pointer knobs and labels, the alarm time can be read off without having to devote electronics to that job.
A programmable diode matrix is used to generate triggers for additional services, for example switching on the exterior lights, with a different time during the weekend.
Home Page . . . . . . . Email: . . . . . . . . neelandan-at-gmãil·çöm