Transistor Clock


This clock uses a combination of individual transistors, resistors, capacitors, and diodes to produce a fully functional clock. What's unique about this clock is that it doesn't use any integrated circuits. This represents the technology that was available in the early 60's. Time is kept by the 60Hz AC signal from the outlet. The 60Hz signal is divided down to a 1Hz pulse to increment the seconds once per second. The seconds and the rest of the time are counted by Binary Coded Decimal (BCD) counters all daisy-chained together (5 total). The BCD is decoded to decimal and then is fed into a decimal to 7-segment decoder. All of the logic used in this clock can be represented by around 19 individual TTL logic chips as shown here. Here is the website of the original creator of this transistor clock. It took me about a week to solder all of the components to the board. I had fun building this clock and it works great. I still need to make a case for it. I've been putting off making cases as you can see on my other projects. I'll probably end up attaching a plexiglass sheet on both sides of it.


I finally made a plexiglass case. There are two panels and 4 bolts holding everything together.


Parts List:

-182 Transistors

-379 Resistors

-560 Diodes

-94 Capacitors

-(6) 7-Segment Led Displays and 4 Leds for the colons

-A Total of 1,225 Individual Parts!

The clock measures 10 in. wide by 13.3 in. high




All of the parts before building.


Last updated May 2010

Contact: Tai Oliphant

Copyright © Tai Oliphant 2010