Nuts and Volts - January 2018

■ FIGURE 4. Electronic Ouija insides.

c := Alphas[c - “A”]
fade_up(c, tcolor, FADE_UP_MS)
fade_down(c, tcolor, FADE_DN_MS)
 pub show_number(c)
 
 c := Numbers[c - “0”]
 fade_up(c, tcolor, FADE_UP_MS)
 fade_down(c, tcolor, FADE_DN_MS)

The show_string() method loops through the characters of the string, passing each to the appropriate handler. The handlers (e.g., show_letter) convert the characters to a channel number. Each of them uses a channel map so that any character can appear on any channel. If you build a project like this, you will need to adjust the maps. This mapping strategy also allows us to define a group, as is used with Goodbye.

you explore the program, you’ll find very simple methods to fade a single channel or a group of channels up or down.

This is a fun program because it’s very simple and can be applied in many ways. John used it for Halloween, but the suggestion originally came from several prop builders who work in the escape room industry. The structure of the base code makes it very flexible.

The single channel methods get the most use in spelling out words that are not part of the command list:

pub show_string | len, idx, c

For example, it would be very easy to control other outputs via the BLE interface; this opens up a lot of interesting possibilities.

Build It, Johno!

 len := tbuf.size
 
 
  repeat idx from 0 to len-1
 c := buffer[idx]
 case c
“““““““A”..”Z””: show_letter(c)
“““““““0”..”9””: show_number(c)
“““““““““““““““: time.pause(FADE_DN_MS)
pub show_letter(c)

John enjoys woodworking, so that’s where he went with this. His first task was deciding how to deal with the numbers and letters. While at a local craft store, he happened upon translucent plastic discs. After deciding on a fairly traditional layout, he cut holes in the top panel for each of the letters and numbers. Before installing the plastic discs, he used the top surface as a template to mark the inside of the back panel so that he knew exactly where to position the lamps. You can see this in Figure 4. Rub-on letters were applied to the discs and then glued in place. The next step was to frost the backside of the discs to enhance diffusion. Of course, he used our own HC- 8+