This Circuit Sculpture Clock Is Completely Functional
Maarten Tromp built this awesome circuit sculpture clock that displays the time like an analog clock.
Circuit sculptures were all the rage for a couple of years. And while that trend seems to have died down, we do still see some awesome sculptures every now and then. But most circuit sculptures are more art pieces than practical devices. They look cool, but are rarely designed for actual use. That isn’t true of this circuit sculpture clock designed by Maarten Tromp, which is completely functional and useful for telling the time.
This clock is digital, but it displays the time like an analog clock. 60 LEDs arranged around the outside ring indicate the minutes, while 24 LEDs on the inner ring show the hour. There are 24 LEDs on the inner ring instead of 12 in order to provide half-hour marks. The LEDs at the 5-minute marks along the outer ring illuminate in a dim light to help people visualize the clock positions. Like most circuit sculptures, the structure of this clock is a combination of thick wire and the components themselves. The thick wire (2mm diameter steel wire, in this case) both adds physical support and provides a circuit ground for the electronic components.
A Microchip ATtiny13A controls the clock, but it only has 6 I/O pins and that obviously isn’t anywhere close to enough to control all 84 LEDs directly. So Tromp daisy-chained 12 SN74HC595N shift registers to control the LEDs. Tromp used PWM (pulse width modulation) to control the brightness of the LEDs, which would normally be difficult to do with so many LEDs connected through daisy-chained shift registers. But because only a handful of LEDs are lit at any given time, PWM works here.
Tromp also got creative to keep time. The ATtiny13A microcontroller isn’t capable of accurate timekeeping on its own. Most makers would choose to add an RTC (real-time clock) module to handle that, but Tromp didn’t need that extra component. Tromp lives in the Netherlands, which has 230V mains power supplied at a very stable 50Hz. Tromp was able to connect the mains power from the power supply’s secondary transformer coil to the ATtiny13A through a resistor. The stable 50Hz frequency gives the microcontroller a way to keep fairly accurate time. That isn’t perfect (and wouldn’t work at all in some countries), but it is good enough for this application — though the clock’s time will probably drift eventually.
The result is a simple and beautiful clock, which ups the ante in the circuit sculpture game.