Unknown Domain

Rebecca Baumann

Rebecca first contacted me in October 2010 looking for some help manufacturing 500-1000 split flap display modules however like me she had contacted Solari and they had been too pricey and she also asked about reclaimed units in the UK as she also had no luck in Berlin.

We spoke a little but nothing came of it, I just emailed her for an update but looked at her website and found she used another approach only recently, she used flip clocks and replaced the existing flaps with custom coloured ones.

She has produced two versions, Monochrome (blue) and Colour Field and it is something to beholden to.

It’s interesting to see that a recent project by Jason Bruges Studio is very similar, either inspired by or working with Rebecca.


Emails from various people

Having had the Twitter Display v1 photos on my portfolio and being that Google is spartan of any useful results several people have contacted me over the years regarding my display, looking for help making their own, to name a few:

Two companies were interested in it for a office ornament…

  • RG/A
    Zoltan Csaki contacted me about something for the London office.
  • IDEO (Randy Plemel)
    Contacted me asking about something for the Chicago office.
  • Rebbecca Baumann
    Contacted me asking for help / advise on building a unit for her art project.
  • Media Lab Toronto
    Patrick Dinnen contacted me to get help working on his own Split-Flap project which I suppose is still in the works as there is nothing on his website about it.

I originally got in touch with someone at Network Rail (Tom Chaffin) about their old units back in 2009 but even then there was nothing about, too late I guess, however he did have some photos for me but I can’t find them any more, he did have a interesting little bit of information about the recent history of the units within the UK rail industry:

The split-flap indicators where widely used for customer information systems on the railway, but the final installations have now gone on National Rail – the last I was aware of was the large main departure board at Liverpool Street and some small displays in the ticket office at Lewis; I forget the exact date, but I think Liverpool Street has been replaced by LED panels for over a year now.  I know for sure that there are none left in service as the Network Rail maintenance standard to maintain them has now been withdrawn – the standard no longer has any use.


The majority of the flap indicators where supplied by an Italian company, Solari SPA and as such these indicators were often called ‘Solaris’ by railwaymen in much the same way as vacuum cleaners are called ‘Hoovers’ whomever the manufacturer is.  However, some flaps indicators were also supplied from a company, I think German, called Krone.


The newest indicators consisted of a number of modules, each module having 80 flaps – each module therefore being able to display 80 different sets of information, though inevitably there would be at least one blank in that set of 80.  Earlier modules had just 40 flaps.  The flaps were printed both sides with sets of information – this varied from a set of a group of stations split over the two flap sides to final destination split over two flap sides – i.e. the two together would show “Victoria” or similar.  The flap spindle was driven by stepper motors with electrical contacts or I think in some cases optical sensors being used to ascertain the position of the spindle and hence stop the motor once the module was displaying the correct thing.  One of the major disadvantages of flap displays was that every time the timetable changed altering train service calling points or final destinations changed or even for a train company name/branding change, new flaps had to be silk-screen printed and then inserted into the indicators ideally the night of the timetable change.  The new main departure boards such as those at Liverpool Street, Victoria and Charing Cross had the columns of flap modules pivoted top and bottom, so to change the flaps it was possible to turn the column through 180 degrees and change the flaps from the inside.  With older displays a tower or ladder was required to work from the outside.      The displays were built up of a number of modules, from typically just two for a single-sided platform next train indicator to many rows and columns of modules for a large departure board at major terminal station.  We never used flaps where one module was used for individual letters – hence this problem with having to change the flaps when the stations changed would not exist, albeit with the drawback of a far more complex and expensive display required, but airports did (and may even still do somewhere) have displays formed in this way.


One of the great advantages of flap indicators, which other alternatives have not fully addressed, though they are now getting close, is their readability under all lighting conditions and viewing angles.  There disadvantages was the need to change flaps, as above and the ongoing maintenance cost for something which is electro-mechanical.

Solari Udine

Way back in 2009 I spoke with a chap called Riccado at Solari Udine who gave me a approximate quote for them to build my project… €40,000!!!

However he was kind enough to provide a PDF diagram which was interesting, and a photograph of that particular unit in production which as it turns out was installed in an American University Library to show some of the Google search strings of students in the library (filtered of course).

He also provided a word document of how the display was controlled which was based on a PC running a small web server application which acts as the interface, like any modern web API really.

Salient Information Systems

I thought it was a long shot but late last year I contacted Salient who I had seen sold Split-Flap displays way back in 2009 and funnily enough the site hasn’t changed since then, however they basically said:

We are unable to help with this product type in such a small quantity. The setup and production costs for this obsolete technology is enormous and requires a sizable quantity to make it worthwhile. Think Airport or Railway station fitout size project.


Public Private Art Install

By far the closest to a complete project, a fabricated display and control system was a project by Martín Bonadeo, which featured 7 characters


Video of the installation:

Setup of the installation:

Quote from Martín Bonadeo’s website…

A 7 characters split-flap-type device (such as those used in airports and train terminals in the 70) is located at Telefonica Foundation’s main entrance. Each of these modules contains 30 characters including the letters of the alphabet and some punctuation. The board has a total size of about 30 cm. x 7 cm. high. All characters are moved every 1 minutes to stay fixed in a new letter. Only the first and last module will not move but remain always in the same positions, the letter “P” and “O” respectively. The rest of the characters is constantly forming the words “publico” (public) or “privado” (private). This sign is shot and this image is projected from one of the windows to the sidewalk of the Plaza Vicente López (next to the fence). This image has a size of 5 meters wide x 1 m high. The characteristic sound of this technology produced by the board is also amplified and “projected” to the plaza.


More on how this works:


History of the Solari Board

This is a snippet of a video I captured when it was on the BBC iPlayer back in 2009 to save it before it gets lost for ever.

Selection of other videos for curiosity



sjculley virtual display

Although most displays that are rendered graphics are good for effects but useless for reference this one actually helped me to realise that I could use a timing belt to transfer to power from the back of the unit to the main sprocket wheel…

MrMagic74 DIY

This is a more basic but equally interesting because of the encoder system used which a later video at the end of this post shows was used in some installations of these displays, unlike Jave.de’s which used opto encoders to detect how many flaps passed based on a known starting point…

Real unit taken out of action:

Jave.de DIY controller

Early in 2011 a project went around the internets which showed a set of eight rescued split-flap displays which had been hacked to work again using an PIC microprocessor. I although he had some small photos on his blog here:


I decided to get in touch and ask for more which Markus kindly obliged despite his busyness, what I did manage to find out was that they were 52 character units, which is quite highly populated and like I thought the letters were probably screen printed (painted) on to the flaps. He also sent loads of great images which I hope he won’t mind me reposting here for this resource…