■ FIGURE 9. 60 Hz Extraction Logic.
transistor comparators with hysteresis and the
Building the Clock
While you could build this clock on perf-board
by wiring individual components, with over 2,700
connections you would need to be committed — or at
least you should be. Building the clock using the
available PCB (printed circuit board) is recommended.
The board and/or a full kit are available in the
Nuts & Volts webstore at
An interesting aspect of the PCB is that a parts
placement guide is not needed — everything is
printed on the PCB. Check out the parts values shown
in Figures 11 and
12. Building instructions and
debugging hints are in the online manual at www.
nutsvolts.com or my website at
Hopefully, you have learned a thing or two about
top-down design, moving from block diagram to transistors
and also a bit about counters and flip-flops. If you want to
add a course in soldering, consider building the clock. The
resulting wall-mountable clock art will be a great memento
of your time and efforts. NV
■ FIGURE 10. 60 Hz Extraction Circuit.
■ FIGURE 11. Portion of PCB Showing Silkscreen.
■ FIGURE 12. Loaded Section.
July 2009 45