Images of prototypes for a 'nixie' Bargraph clock.
The three vertical columnar neon tubes are used represent hours, minutes, and seconds respectively from left-to-right. A PIC controller is used to control output to an A/D chip, that in turn directs varying current to the tubes to control the degree of illumination of the various tubes.
The 12 horizontal plexi-glass slats are used to gradate respective time intervals. That is,
The intent is that as the illumnation of the tube passes each given slat, that the light illuminates the entire slat. Sort of a climbing ladder of light.
So far, either the degree of polish, or simply light transmission properties of the plexi seem to limit the amount to which the slat becomes illuminated.
Prototype I:
Slats are 1/8", with green tinted plexiglass used to demarkate the quarter-hour points (e.g., 3,6,9, and 12 O'clock). Although atractive, the 1/8" slat width makes accurate reading of the clock a bit ambiguous.
Kepp nuts are used on threaded stock to separate the slats. This is inaccurate, and makes adjusting slat position extremely awkward
Prototype II:
Slats are 1/16". TAP Plastics doesn't carry tinted material in this width, so polycarbonate is used for the quarter-hour points, as it has a slightly more bluish tint. However it is barely descernable.
Aluminum tubing spacers (3/16") are used on metric threaded stock to set slat-position. Metric thread was used because the spacers fit more snuggly than on 1/8" threaded stock.
Future versions may use real glass, or perhaps some separating material in the slats between the tubes to isolate the slat illumination.
Prototype III:
I call this the Pagoda model. Click here for a big version of the really lame annimated gif of the lit 'working' clock you see above. It's and takes a while to load. Be prepared to wait.
Slats are 1.5-inch squares of 1/16-inch plexi, using .5-inch OD tubing for spacers. This tubing is conveniently 3/8-inch ID, which fits perfectly around the bargraph tubes.
Again, threaded stock is 1/8-inch 6-32, with 3/16-inch tubing to hide the threads.
It has the advantage that the 3 tubes needn't be so exactly positioned with respect to each other in the housing; They only need to be accurate with respect to their own stack of slats.
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