The Big Flipper - Four Letter Word In Flipdots

What do you get if you mash up a word association database with some flipdot highway signs pulled out of a bin?

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Four letter word "clocks" have a venerable history as art objects. They used character displays to display seemingly random four letter words, originally generated randomly by custom electronics, then chosen according to a database of words that were chosen by participants in psychological trials when presented with a word, e.g DOOR might lead to OPEN or SHUT, etc. This project uses some old highways signs that were found in a bin. A goal was to make it look interesting.

The main project goal is to have a wall mounted display of 4 characters made from my old highway flipdot panels. Whats a flipdot? you can do worse than look at FredericL's project From my point of view they are an awesome obsolete display technology that is wonderfully mechanical and with superb sound effects when they operate. The operating principle of magnetic remanence, see is a beautiful example of physics in action, and also enabled!

My panels are each 7 x 5 dots, and very large, about 240mm x 350mm, the dot size being about 38mm, so 1 1/2" in old money.

The panels were not in the best shape when I picked them up, and the 20 years that they have been in storage has not improved them. Luckily I have several boxes so I can mix and match parts to get 4 good panels.

I did not find any driver electronics, but in 2015(!) did build an entire 4 panel driver board using motor driver ICs but it never worked so I shelved it. So I either have to resurrect it or build another driver.

Then I want to display seemingly random four letter words on the display chosen from a database of word associations. The original idea of the four letter word database I owe to akafugu, who sells the database as an addon for his VFD clocks: I am not sure if he originated the concept of using the database, but I can't find an earlier example than his project punished in 2012.

  • Flipping!

    Tom Harris20 hours ago 0 comments

    This is out of sequence but I have been on a roll getting the driver electronics going and chasing hardware problems that caused driver chips to meltdown!

    Here's a video of The Big Flipper running a simple test pattern:

    And here's one of it streaming words fairly fast, actually about half the maximum update rate.

    Sorry about the poor quality and the  mess in the workroom but these are in the nature of an interim update. And I suppose I should give back the ironing board.

  • Panels all fixed up

    Tom Harris06/07/2021 at 22:16 0 comments

    I managed to get 4 complete working panels. Many of the small plastic holders for the dots have broken, they are amazingly delicate. I imagine that once installed and out of the weather they would have been reliable enough. As I mentioned previously every dot worked fine once it was mechanically whole again. I suppose with solenoids and diodes there's not much to go wrong.

    Note to self: always set all dots to visible, so that they are horizontal. They are less likely to get damaged.

    What a beautiful sight, 4 working panels.

    An entire panel's worth of broken dots. Most are fixable if I find some glue that will work. But I could 3D print replacements I suppose.

  • Making the Flippin' Thing Flip

    Tom Harris05/28/2021 at 11:41 0 comments

    I should say how to make a panel flip. If you look at FredericL's project and watch Lansing Maker's Network excellent video on the Flipmaster9000(!) on Youtube then you will know all about how they flip.

    So you will see that they are wired in a matrix of one column connection, and two connections for each row, which I call H & L. Current will only flow into the H row connection (so positive DC to H, negative to common), or flow out of the L connection (so negative DC to H, positive to common).

    I now had to identify the row and column connections. On the back of the panel are a 40 way header marked COLUMNS and a 34 way marked ROWS. I did some continuity tests and noted that the column pins are commoned 1 through 8, 9 through 16, up to 32 through 40. Pins 1 &2, 3 & 4, etc are commoned on the row pins. Now I set a bench power supply to 30V, current limit 250mA and started poking current through the panel. I guessed that this current could not damage the panel provided that I did not keep it connected for longer than a fraction of a second.

    What I found surprised me, neither the rows or columns are in sequence. Probably this was done as the PCB for the panel is single sided, so the designer didn't want any wire links. Also the row L connections set (dot visible) some rows, and clear (hide dot) others. Again this must have been done to make the PCB easy. But it complicates the driving, at least as it will be done in firmware that will be easy.

    Anyway, here's a table of connections. Columns are numbered from the left 1..5 and rows numbered down 1..7.

    1..8: C2

    9..16: C1

    17..24: C3

    25..32: C4

    32..40: C5

    1, 2: R7L (clear)

    3,4: N/C

    5, 6: R7L (set)

    7, 8: R6L (set)

    9, 10: R6H (clear)

    11, 12: R5L (clear)

    13, 14: R5H (set)

    15, 16: R4L (set)

    17, 18: R4H (clear)

    19, 20: R1H (set)

    21, 22: N/C

    23, 24: R1L (clear)

    25, 26: R2H (clear)

    27, 28: R2L (set)

    29, 30: R3H (set)

    31, 32: R3L (clear)

    33, 34: N/C

    An example: to set dot on row 3, column 2: positive on R3H, negative on C2. To clear it, negative on R3L, positive on C2.

  • Fixing a Flipdot Panel...

    Tom Harris05/28/2021 at 11:00 0 comments

    I took one panel and had a good look at it. As can be seen, there are quite a few breakages.

    These need fixing else the yellow dot will fall out as it will not be secured properly. I tried gluing them with superglue, but it did not work well on the plastic, which is some sort of very brittle glass filled stuff. I suspect that it will need epoxy glue to do a proper job, so I'll do a whole batch at once to avoid wasting glue.

    So I selected the most beat up of my five panels as a donor and started taking it apart. The rows of dots rotate on a thin steel wire, which can be carefully removed by pulling with pliers. Like so:

    And then I ended up with this. All 35 dots are in one piece and rotate freely. Now to check if they actually work. I did this last as I have never found an electrical fault with these panels, somehow they are super reliable.

  • Grabbed the flipdot panels from the shed.

    Tom Harris05/28/2021 at 10:37 0 comments

    The answer's in the shed, now what's the question?

    I started this project by a happy coincidence: I was looking though my store of *stuff* and found several boxes of flipdots that I scored when I was working next to a highway sign maintenance company; and I read on Hackaday that they had a contest involving retro technology.

    So I pulled out one box of flipdots. Unopened since 2015.

    In here were 5 flipdot panels, each 5 x 7 pixels. Here's a photo of 4 of them arranged so as to give an idea of the final clock. The ruler is 600mm. Please ignore the photobomb from my Hoke's Long Weight, the object that many apprentices have been sent to ask for but somehow is never in stock...

    As you can see many of the disks have become loose, due to the plastic carriers getting broken, they really are very delicate.  Tonight's job is to get one panel in good order so that I can document how it works and how it is connected.

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