Earlier this year, we mentioned in a Hackaday Links article that [Spencer Hamblin] was in the process of building a seven-segment flip clock. Well, it’s finally finished, and it looks great!

Vintage seven segment digits make up the display. These digits work the same way that flip-dot displays work – current through each segment’s coil creates a magnetic field which causes the segment to flip over. Current in the other direction creates the opposite magnetic field and flips the segment the other way. On these digits, there are three connections on the coils. The middle one is power and the other two are used to enable and disable the segment – ie., flip it one way or the other. To save on pins on the microcontroller, [Spencer] connected all the middle coil pins together on a digit. Each coil can be powered using a single pin on the microcontroller. Similarly, the segments for each digit are connected together as well, so one pin on the micro controls the same segment on each of the digits. The microcontroller in question is the AVR ATMega48.
There are two parts of the clock face left to do: AM/PM and whether the alarm is set or not. [Spencer] used a fifth digit, slightly offset, for those – the top and middle segments are used.
For the housing of the clock, [Spencer] used layers of offsetting colored wood. The wood (sapele and ash) were CNC cut and aligned. The back plate, also made from wood, holds buttons for setting the time and alarm, as well as some LEDs for what [Spencer] calls the “daylight alarm.” A capacitive sensor on the top of the unit (inside the wooden case) is used to turn the alarm off.
The result, after sanding and shellacing, looks amazing. [Spencer] nailed the art-deco look he was going for. There are plenty of pictures and the circuit designs, schematics and code are on [Spencer]’s Hackaday.io page, and you can find the Hackaday links post here. This is a complete log of a project we mentioned earlier on Hackaday, here, but there are other mechanical flip display clock projects, such as this DIY mechanical flip seven-segment prototype, or, you could create your own (really big) clock using this Lego mechanical seven-segment display.
via Reddit.




He starts off by building a custom electro-mechanical clock movement, and since he’s planning as he progresses, meccano, breadboard and jumper wires were the way to go. Hot glue helps preserve sanity by keeping all the jumper wires in place. To interface with all of the peripherals in the clock, he decided to use a bank of shift registers driven from a regular Arduino Uno. The more expensive DS3231 RTC module ensures better accuracy compared to the cheaper DS1307 or similar clones. A bank of RGB LEDs acts as an annunciator panel inside the clock to help provide various status indications. The mechanical movement itself went through several iterations to get the time display working with a smooth movement of the hands. Besides displaying time, [David] also added a moon phase indicator dial. A five-rod chime is struck using a stepper motor driven cam and a separate solenoid is used to pull and release three chime hammers simultaneously to generate the loud gong sounds.
