A while ago I got my hands on some old split-flap displays from a train station. Yesterday I finished driver circuits for 8 of the segments. It was only just in time to also quickly implement a clock algorithm for an extraordinary clock to display the turn of the year. Don’t miss the movie at the end of this posting.
The original driver circuits consisted of a Zilog processor, an EEPROM, an optocouppler for driving the 42V synchronous motor, transistors, two reflective IR-sensors for segment position and a few passive components. Since I do not have any information about the original interface and protocol, I decided to implement my own driver circuit and directly connect to the sensors and motor.
I am still not sure what project to use my rgb 7-segment display for. There were some very interesting ideas posted to the Hackaday forum. I like matthiasrs idea most: A 2-digit clock, using the red LEDs for hours, the green ones for minutes and the blue ones for seconds.
In order to get a better idea, rather then implementing it in hardware I wrote a little simulation as Java applet. Have a look and see how hard or easy it is to identify the time 🙂
7-segment LEDs are available in red, green, yellow and blue (maybe even in white?). There don’t seem to be any in RGB though, so if you want to dynamically use different colors in your project you either have to use multiple devices or use a different technology.
So this seemed like an opportunity for a nice DIY project: Why not take an existing 7-segment display, remove the original LEDs and add some RGB ones? (continue reading…)