IBMsold its US Time Equipment Division to Simplex at the very end of 1958, but I still serviced these clock systems with
IBM maintenance back in 1967. In 1966, I purchased the
IBM master clock shown in Photo 2 from a fellow IBMer,
but my master had its contact assembly removed before
I bought it. You can see original wiring and the contact
assembly of a master I repaired for a friend in Photo 1.
My master clock was originally installed at International
Paper Company's Southern Kraft mill in Panama City, FL in
1930, but because of the missing contact assembly it can
no longer control secondaries. Two of my most cherished
secondaries (Photos 3 through 6) came from the same
paper mill, and another one (shown in Photo 7) came
from Cove Elementary School where I attended the
second through sixth grades.
Since the day I acquired my first IBM secondary clock
movement, I've wanted my own clock system. I did
manage a couple of feeble attempts at making my own
contacts, and even purchased a BASIC Stamp for the
project. However, I procrastinated (about 46 years) before
finally building this computerized version of a master. Of
course, the Arduino Mega 2560 I received as a Christmas
gift helped motivate me.
These electronic masters (Photos 8 and 9) are far
better and much more accurate than the brass, nickle, and
mercury master clock living in my foyer. Even better, I now
have all five of my IBM secondaries clicking away in my
January 2015 33
Post comments on this article and find any associated files and/or downloads
This article describes a computerized equivalent
master clock for an IBM minute impulse self-regulating clock system. So, if you are lacking a
functional master, build this project and get one
or more IBM impulse secondary clocks working
accurately and electronically. Information here
may also help you control other items by using
the popular Arduino project computer and an
insulated-gate bipolar transistor (IGBT) MOSFET
device. For instance, you could drive a high
current unipolar stepper motor winding with
the Arduino and an IGBT device the same way.
■ PHOTO 2. My 1930 IBM master clock.
■ PHOTO 5. Model 561-2
movement of clocks in
Photos 3 and 4.
■ PHOTO 6. Model 563-2
movement of clock in
■ PHOTO 3. Impulse
secondary from executive
offices. Soft copper shell,
brass numerals, scripted
"International," and minute
markers each screwed to a
■ PHOTO 4. Impulse
secondary from engineering
dept.; soft copper shell and
■ PHOTO 7. Impulse secondary from Cove Elementary.