There’s just something about electro-mechanical displays that enthralls most people when they see them; and while you’ll be hard pressed to find a split-flap display for cheap, you can still easily buy flip-disc displays! That’s what [Scott] did, and he’s been having a blast messing around with his and building a system to control it via his Android phone.
He picked up the display from a company called Alfa-Zeta in Poland, a company that’s been making electromagnetic displays since 1988. No mention of price, but it looks like some pretty awesome hardware. The beauty with electromagnetic displays is they don’t consume any electricity in idle state, making them far more efficient than almost any other display technology – not to mention perfect contrast in any lighting conditions!
They work by using permanent magnets, electromagnets, and a material that can retain magnetization. A short pulse to the electromagnet causes the disc to flip into the second position, which will then hold in place due to the permanent magnet — no more electromagnet needed.
The display comes with all the necessary hardware to drive the electromagnets and interface with a microcontroller. But, it uses the RS-485 standard, which isn’t natively supported by most other microcontrollers. [Scott's] using an Arduino which does have an RS-485 shield, but he decided he wanted to challenge himself and build a circuit to drive them himself!
All the info is on his blog if you’re looking to try something similar. Once he had it interfaced with the Arduino it was just a simple matter of writing an Android app to transmit controls over Bluetooth for the display. Take a look: