Just around a week ago, I was at Pittsburgh Zoo. I figured that when I got to the Tropical Forest area, I would check out that sign...
Turns out that it was not on the wall that I thought it was on.
When I read the variable portion, I noticed that only two of the digits were mangled up. Also, the display was changing much faster than I remember (50x faster), and the changing digits were a lot louder than I remember. (Maybe I was working with the 4-inchers so much that I could hear the 1.5-inchers in the sign working.)
The 1.5-inchers aren't all that loud when they change.
The marquee you made looks nice. I could possibly maybe get the schematic and try to copy it down for a larger marquee using more lights in the sequence.
I've actually planned out a different eggcrate digit build with pre-wired character set (1-2-3-4-5-6-7-8-9-0 and dollar sign).
I would make different sizes of eggcrate digits.
The smaller digits (for toll plazas, arcade games, etc.) would use bi-pin bulbs on a board and two rows of six pins in DIP format for connectivity.
Medium-sized digits (for clocks, outdoor signs, small scoreboards, studio applications, etc.) would use slightly larger bulbs (G4.5 up to S6) under a foam mask and use a six-by-two set of pins for connectivity.
Large digits (for clock towers, scoreboards, and advertising boards) would use special 6- or 12-volt bulbs in a grid and use a three-by-four female header for connectivity.
Since the digits would use a pre-wired character set styled like on Wheel of Fortune and The Price is Right, there would be no need for a special chipset to drive the display – just use a BCD-to-decimal decoder with an extra output for the dollar sign on the binary input "1010"!
And if you want a decimal point or colon separator, use light bulbs of the same type/voltage connected to a separate signal from the digits for each decimal point/colon separator in the display.
Well, the schematic is just every pin on port A going to a 470ohm resistor and to two transistors, driving two bulbs at a time. That's really just about it apart form the buttons.
Sounds nice and simple to me! Alternately you could use the CD74HC4067 and have up to 16 characters.
I have to say, it's a lot simpler than trying to scroll digits across a matrix. (Even scrolling a single byte was work enough. >_<) I have a clock in mind with fixed 3x5 digits. Maybe someday. I figure it'd be nicer and easier to read than a single digit 5x7 clock with too many settings. X3
Okay, so I would just connect every pin on port A using a 470 ohm resistor and two transistors to drive two bulbs at once. (And I'm guessing the resistors would be used to prevent thermal shock...?)
How I would drive the digit would be to use a CMOS (5 or 12 volt) or TTL (5 volt only) BCD-to-decimal decoder IC for the inputs for pins 1 through 10 (the numerals). Pin 11 (the dollar sign) would use a separate signal, and would be triggered upon an input of binary "1010". "1011" through "1111" would blank the display.
Of course, I'll need help with setting up transistorized gates for the separate signal. Otherwise, it'll only show the numerals.
Some applications wouldn't need the dollar sign. Take the arcade game application, for example – the credit, score, jackpot, and ticket payout displays just show numeric data without any extra symbols.
If you want to get fancy with your eggcrate display, use a sheet of colored cellophane behind the lens to color the display. This would look especially appealing on an arcade game, for the jackpot display or the score display. Normal colors used on eggcrate displays are red, green, amber, yellow, and blue, but you can go fancier and use either purple or pink. (A smoke filter can be used to darken the display, or the filter can be omitted altogether for a normal white display.)
Well, since RadioShack carries the the miniature bulbs I'm looking for (cat. no. 272-1154), I got myself four of those and two small PC boards (cat. no. 276-158).
I placed the four miniature bulbs on the board in a vertical line pattern across the center of one of the boards (columns L and M; and rows 9, 13, 17, and 21) and placed a few strips of tape over the bulbs to prevent them from falling off.