If you are looking for a simple analog computer to calculate time zone differences, you can’t go wrong with this one, from the February 1944 issue of QST. It had been sent in to the magazine by one Lt. I.E. Slutzky, who found the need for a simple device for changing time at one location to any other location on the globe. Since this one had scales for “yesterday” and “tomorrow”, it would also simplify those vexing questions surrounding the International Date Line.

In 1944, you would have had to meticulously re-draw the design (or perhaps cut up your magazine). Today, however, you can easily print the image above on two pieces of cardstock. If Junior is in need of a science fair project, this one will allow him or her to construct an analog computer.