3

How I Made: Time-to-go-clock

FEATURE

Components – the rest

• Arduino Mega or clone equivalent –
  although GRA & AFCH say the Clock
  shield would work with an Arduino
  Uno, in my implementation I needed
  the pins and extra processing grunt of
  the Mega.


• Arduino Ethernet shield or clone
  
  
  • if I were to do this project again I’d
    probably try to use an ESP8266-based
    board for connectivity, but at the time
    I was more comfortable with the
    Ethernet shield.
  
  
  
  


• I^2 C 20 × 4 LCD module. The display
  serves several useful purposes. It
  indicates what mode the Nixie tube
  display is in, greatly simplifies setting
  the future time being monitored, and
  indicates the time the clock has (or
  will) tweet that day. Another reason I
  included it though was as an example
  of a display technology that spelled the
  end for the Nixie. More practical, much
  cheaper, but hardly a thing of beauty.
  Take your pick.


• Rotary encoder. The Clock shield
  comes with some momentary button
  switches which can be used for setting
  the clock. However, the additional
  functions of the clock would make
  button control alone very cumbersome
  and in any event they are not accessible
  in my enclosure design. The B&K
  actually uses a very nice rotary encoder
  as part of its own control scheme
  which I could have reused. However,
  the B&K’s encoder did not incorporate
  a momentary switch, which meant you
  could not easily select an option dialled
  in using the encoder.


• Switches. The rotary encoder
  working with the LCD display allows
  many setting and control functions to

be combined in a user-friendly way.

However, for some functions you

just cannot beat the convenience

and satisfaction of flipping a sturdy

toggle switch.

• Potentiometer. Used to control
  dimming of the backlight on the
  LCD display.


• IR motion sensor. Some Nixie clock
  implementations use a timer feature to
  turn the tubes off at night or other set
  intervals. This doesn’t seem entirely
  sensible to me – much better to use
  this $5 motion sensor, which works
  incredibly well. The clock also logs the
  last detected motion on its website,
  a feature which I find very useful for
  reasons that need not detain us here.


• 12 V 1 A power supply. The driver
  board shield is designed to take 12 V
  power from the Arduino Vin pin, so a
  12 V supply is a must.


• Miscellaneous consumables such
  as jumper wire, crimp connectors,
  grommets, heat shrink tubing, etc.

That might sound like a lot, but with a bit

of careful shopping the whole lot (minus the

enclosure) can be had for not much more

than $150.

TOOLED UP

All you need to complete this project is a drill

(ideally with a step bit), a soldering iron, a

multimeter, and various hand tools. As with

most projects, if you have more stuff, you

will probably find a use for it. I drew upon

many different resources for the coding side

of things, primarily Google. Other search

engines are available.

Preparing the enclosure

I removed some of the B&K’s electronics

and power supply to give me plenty of room

to work. The hardest part by far (and even

this wasn’t too difficult) was drilling the

six holes for the Nixie tubes in the top of

the case. Two additional, smaller, holes are

also required for the digit-separating neons.

Alignment of all these holes is obviously very

important and this is the one time when not

having the board pre-populated would help. I

considered various ways to get the alignment

right but in the end used the simplest

method. After drawing a line across the case

Left

Stripping back the

front panel revealed

just what I had to

work with

Left

The clock cycles

through different

ways of displaying

the time left