What is the Analog Style LED Clock and how does it work?

Senior Project - Analog Style LED Clock
Senior Project – Analog Style LED Clock

The clock was originally designed as my Senior Project to complete my Electrical Engineering Degree. A number of years ago, I remember reading about a technique to individually control a large number of LEDs with a relatively small number of I/O lines. I immediately thought a good use of this technique would be to make a clock with 180 LEDs. It would have 60 LEDs each for seconds, minutes and hours (which would increment every 12 minutes). It never became much more than an idea in the back of my mind until I suggested it to my instructor for my Senior Project. He responded that he would accept the proposal if I added an alarm feature.

The goal originally was to independently drive 180 LEDs, read two pushbuttons and monitor the 60Hz line, all with an 18-pin processor. I decided that I would add a buzzer for the alarm, an “Alarm” LED, a “PM” LED and two more pushbuttons … and not increase the pin count of the processor!

How was this made possible? The picture above shows the completed project. All of the components are visible. There are no hidden components, no other driver circuits. The LEDs are regular high-intensity LEDs; nothing special about them. A total of 182 LEDs, 4 pushbuttons, a buzzer and monitoring the 60Hz line … all ran by just the 18-pin controller in the center of the board!

This project generated a lot of interest while I was developing it. As a result, I have decided to offer the project as a kit that you can build yourself. An assembly, operation and technical manual is included, complete with theory of operation, schematics and drawings. Check out the Analog Style LED Clock Kit!

Questions? Comments?

Please contact me if you have any comments or questions.