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Another mistake

A project log for Numitron Hexadecimal display module

Another hexadecimal display, this one is sans transistor for the extra vintage touch, and uses only Soviet-era parts

Yann Guidon / YGDESYann Guidon / YGDES 10/24/2017 at 23:522 Comments

Do you remember this picture from the last log ?

OK and now, let's think again about how the diode matrix was optimised.
The short version is : the digits 5, 6, D and E are bork.

This means that my carefully optimised diode matrix is invalid. I have to swap 6 and 5 before optimising to preserve coherence...

The swapped array:

^ ^v^v^v^v^v^v (0, 8)
^ ^   ^ ^v^v^  (1, 9)
^v^ ^v v^ ^v^v (2, A)
^v^ ^ ^v^v v v (3, B)
 v^v^ ^  v v^  (4, C)
^v^v^v^v v  ^v (6, E) \ swap !
^v v^ ^v^v^  v (5, D) /
^ ^ ^    v v^v (7, F)

The new optimised array :

   v^v v     v (0, 8)
      ^  v^ ^     X4
^ ^     ^  v      X2
     v    ^ ^  (2, A)
 v  ^  v     v    X4
      ^  v     (3, B)
           v   (4, C)   (2 ^ to remove)*
 v^v  ^     ^     X4   (2 ^ to add on A and F)
^    v v     v (6, E)  (1 v to add and 2 ^ to remove, swap with 5)
    ^    v        X2    (unchanged)
 v v  ^v^ ^    (5, D)  (1 v to remove and 2 ^ to add)
^            v    X4 (2 ^ to remove)
  ^        v^  (7, F)   (2 ^ to add, reusing those of 4)

So I have to rewire quite a few diodes... Half of them in fact ! Well, not really, because some of the changes are rather symmetrical. For example, the X2 line is not changed and instead of removing LEDs from line 4,  the LEDs can be rewired to line 7.

This gives you an idea of the rework that awaits me:

Discussions

add_ocean wrote 10/25/2017 at 18:46 point

looking at the photo of display unit...

oh my God. Looks like numitron becoming a supplement (secondary) display in this case :)

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Yann Guidon / YGDES wrote 10/25/2017 at 18:51 point

It's part of a whole "totally visible" design philosophy :-)

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