Way way back in 2012, when I made the first post about the nixie chessboard, I said ‘This developed as a spinoff from the hardware and controllers I’m designing for a range of nixie clocks and watches as a ‘simple’ project that wouldn’t need much software to complete it.’
Just over four years later I’ve finally finished the first of the nixie clocks that inductive power technology was intended for and you can see why losing the power cable was essential:
Power is coupled from a coil in the levitation base to another wrapped around the base of the floating case in exactly the same way as the original 2012 chess pieces. It’s rectified and used to power the tubes directly, with a very small amount being reduced to 3.6V to feed the logic and LEDs.
The base communicates with the floating display using an infrared LED to transmit the time and display settings commands. I did use serial data encoded on the PWM signal used to drive the induction power coil but it tuns out modulating the current through a coil mounted on top of a large magnet at 9600BPS has interesting side effects 🙂
The clock software is almost the same as our V1 5-tube clock, modified a little where required to allow control via a Bluetooth receiver and touch switches in the base. The display mode can still switched between HH:MM, MM:SS and DD:MM by the ‘hand-waving’ proximity detector. All the other features you’d expect are there, including the infamous ‘random length second’ option.
Power is supplied from a qualty ‘laptop’ style brick providing 12V at about 3A – much the same as supplied with the chessboard which is built into a ‘power pack’ box along with a battery pack made up of 8x Alkaline 1.5V ‘AA’ cells (batteries not supplied of course).
The batteries will keep the electromagnets running for around 20-30 hours to hold the clock in place if power is lost for any reason. Although it normally draws about 5-600mA, when first floating the clock it’ll pull up to a couple of amps as the elctromagnets ‘pull in’, quickly dropping to it’s normal level.
Cushioning under the floating magnet and in the base reduce the shock if the clock does drop, usually due to over-enthusiastic prodding or spinning. In all the months of testing and dozens of drops – both intentional and not, some with no cushioning in the early days – we haven’t lost a single tube.
You can find plenty more images and videos over here on the Kickstarter itself: Time flies-levitating nixie clock