Making Time

Enter Your Electronics & Design Project for a chance to win a $200 shopping cart!

Submit an EntrySubmit an Entry  Back to homepage
Project14 Home
Monthly Themes
Monthly Theme Poll


When the Making Time competition started, my long-term memory forced my thoughts back into 2011 (sounds like a virtual time machine) when I was prototyping a sundial based on a regular clock movement and some LEDs, called a bulb dial.


It all started from a blog post with just a beautiful concept drawing at Ironic Sans (amazing the the blog is still up 13 years later). The idea is simple and elegant. 3 light sources circle a pin and cast shadows in different length for hours, minutes and seconds.

Bulbdial Concept

The idea of a bulb dial got picked up by several parties and got implemented with boatloads of static LEDs.

First were the geniuses at Mad Evil Scientists. I am not affiliated with them, just want to give them credit where credit is due.

Other implementations can be seen from Solarbotics and Taufeeq.


My Bulbdial

My bulbdial


The idea was cooking in my mind for some time until I had enough pieces of the puzzle solved to build a prototype in the spirit of the original concept. I needed a mobile means of power transfer between the different light levels. The solution was multiple disks of decreasing radius for hours/minutes, stacked on top of each other with a shadow casting pin in the center and LEDs of different heights at the edge of each disk. Energy transfer was done through concentric rings of conductive material on the lower level and spring loaded wiper contacts coming down from the upper level. Wires, LEDs and current limiting resistors were the easy part. LEDs had to be narrow beam types, additionally enclosed in heat shrink/tape to reduce stay light all over the place. In the true spirit of prototyping I used wobbly disks of cardboard, copper and aluminium tape and copper EMC finger gaskets.

The clock movement was a continuous type with all arms running smooth in circles and not hopping from one second to the next. Contact was not perfect, so the LEDs went dim/off randomly, so I tried to improve contact resistance with solder and more conductive tape.

In the end, I could prove the concept, but never got to a good enough prototype that I would put on the wall as a working timekeeping piece.


Here are some pictures and a video of the (almost) working prototype.

{gallery} My Bulbdial

Bulbdial: The working prototype

Contacts and the pin: Bottom side with copper slide contacts and the shadow-casting pin.

Sliding Contacts: Copper contacts with added solder for better contact making.

Contact Rings: The middle disk with contacts and an LED in black heatshrink tubing

Contact Rings 2: More contact rings made out of copper tape at the clock base with feed wires


This is how it looks like in action:



Looking into the future

(More virtual time-machining in the positive direction of the time axis.)

When the project moves up high enough on my procrastination to-do list, I want to make real PCBs with trace inductors for wireless energy transfer to get rid of the wiper contacts.

Attached is an article, that implements a very simple wireless energy transfer. The plan is to have a single PCB, that can be populated with components to be either transmitter or receiver and it has to work with 1 tx and 2 rx boards stacked.


Cheers to the present and time will tell what the future brings.