Pi Day Quiz 2016

Its time for the annual Edison Tech Center Pi Day Quiz!

2016 Edison Tech Center Pi Day Quiz

1) The Marchant electromechanical calculator consists of several interlocking gears which are driven by an electric motor. If all the gears have a diameter of one unit, and each gear has ten teeth, what’s the total distance the gears travel for the following calculation:

2) The Marchant electromechanical calculator consists of several interlocking gears which are driven by an electric motor. If all the gears have a diameter of one unit, and each gear has ten teeth, what’s the total distance the gears travel for the following calculation:
999 multiplied by 1001

3) In a Synchronous AC motor, the R.P.M.s are ideally equal to (120 X Freq) divided by the number of magnetic poles.
How fast is the outer material of a 1.5” diameter rotor traveling, when energized at 60 Hz on a synchronous, 4 pole motor?
– Question by Shane Pickett, Nidec Drive Systems Engineer

4) The Marchant electromechanical calculator consists of several interlocking gears which are driven by an electric motor. If all the gears have a diameter of one unit, and each gear has ten teeth, what’s the total distance the gears travel for the following calculation:
1001 minus 999

5) A tire company has twenty stacks of tires up to eight tires high, of seven different diameters. What is the most efficient arrangement of the tires to be able to access any tire?
– Question by Gene Bills

6) A machine to weave canvas sacks uses 6 spools of thread evenly placed around a rotating circular spindle. How much more thread is used for a canvas sack with twice the diameter?

7) How much more volume does a canvas sack with twice the diameter of a smaller canvas sack have?


Charles P. Steinmetz Publicity

According to some of us Charles Proteus Steinmetz is arguably the greatest unsung hero of the electrical age. Steinmetz represents the major step from trial-and-error methods of electrical invention to the modern age of engineers where math and science are necessary for innovation.


During the 1890s and 1910s Steinmetz was respected as one of the greatest inventors of the age. He attended important scientific conferences and his inventions and opinions guided the largest of companies. Embarrassingly for Westinghouse, Steinmetz was the only one who could solve problems Ben Lamme and Tesla couldn’t figure out at Niagara Falls. Steinmetz’s mathematics drive the very heart of AC power systems design even today. So why have most people never heard of this distinct and spunky cigar-smoking dwarf?

We were pleased to hear of the new documentary by WMHT (PBS) on Steinmetz. The path to proper publicity starts with a solid documentary and hopefully we’ll see more about him soon.

Steinmetz in his Lightning Lab

Here at the Edison Tech Center we have published several basic videos on Steinmetz and included him as part of other biographic documentaries such as Harold Chestnut, Pioneer of Automation. Our webpage on Steinmetz is one of the top when you search for him, and figures indicate thousands of people have used it to learn about his odd fellow.

The fact is we have a lot more to tell about Steinmetz that we have not published yet, so you can expect more to come from our side in the future. For now you can enjoy these free online videos from the “Divine Discontent” documentary:

Mountain Lake PBS 28 minute extension:

And here is the full 1 hour documentary on WMHT’s site:

DIVINE DISCONTENT – on the WMHT Vimeo Channel

Invention of the Microwave Oven

When the Edison Tech Center published its video with Rudy Dehn talking about how the device worked hundreds of thousands chose to watch it, however many didn’t get the full story. Yes Rudy was one of the guys who made this staple of modern kitchens available, but similarly to most other inventions it took many others to build a foundation. Notable contributors include Albert W. Hull, Kunio Yagi, C.W. Rice, Percy Spencer, and others who all contributed a bit to make the modern oven possible.

Here is a timeline for the microwave oven:

  • 1921 Albert W. Hull at the GE Research Lab in Schenectady, New York develops the magnetron
  • 1924-28 European engineers explore the magnetron oscillator. Zacek (Czech) and Haban (Germany) do work on the subject but don’t apply for any patents
  • 1928 Kunio Yagi works on multi-anode oscillators in Japan. The same year C. W. Rice demonstrates a magnetron transmitter at GE in Schenectady.
  • 1930 General Electric offers type FH-11 magnetron for sale, then later discontinues production due to lack of customers
  • 1937-40 Oliphant develops multi-cavity magnetrons in England, this becomes the first true microwave magnetron
  • 1940-45 Magnetrons were the key components of radar systems
  • 1945 Percy Spensor at Raytheon proposes a microwave oven as a peacetime spin-off of radar. The Radarange is sold to commercial and institutional users.
  • 1945-1950 GE develops magnetrons for industrial processing
  • 1950-1953 GE Range Department developed full size oven using 915 MHz.
  • 1960s GE engineers continue to work on making the power supplies smaller for the microwave oven (as well as many other applications). GE engineers including Rudy Dehn work on making the microwave oven smaller so it can be the modern countertop device we know today.
Dehn two magnetrons
Rudy Dehn holds two generations of magnetrons at the Edison Tech Center. The large device on the left is from the 1950s full sized oven. The device on the right is the compact version used in most today.
  • 1960s Japanese companies buy rights from GE and develop the 2450 MHz oven
  • 1970s Japanese manufacturers dominate the field of microwave ovens due to automated production which reduces overall cost for the consumer

Here are a few of our videos on the microwave oven:



This beast of capacitors and tubes was just the power supply for the 1960s era microwave ovens.
A new HF power supply in a modern microwave oven
1960s microwave
A happy housewife of the 1960s enjoying the fruits of engineering.
Magnetrons and other tubes on display at the Edison Tech Center
Microwave ovens from all decades on display at the ETC
The back of the 915 MHz oven model from the 1950s. The magnetron pokes into the oven cavity directly unlike modern ovens which use a waveguide to bounce waves into the cavity.
The 1953 GE oven model. The microwave oven is on the bottom. There are also calrods in the oven under the turn-table.

Universe of Instrumentation Project Testing

The Edison Tech Center begins phase two of testing on the new Universe of Instrumentation project. We will be monitoring use over the next month to see how people are using the program and formulate how to improve it in the future.

In phase one of testing we published a few articles on Ammeters, Voltmeters, Oscilloscopes and other topics on our static site. We used our older long page format. In this current phase we broke content down into smaller chunks with a simple “previous” or “next” button so users can navigate through in the proper order.

Our mission is to tell the balanced story of innovation, and so naturally we’d like if users would progress from the most primitive technologies up to more recent devices. Even if many of our users are already engineers familiar with how the older technologies work, we usually provide unique information on back stories and the human side of the early devices. In the end each user finds a way to have our pages work for them, whether that is a quick look up of a name of fact, or an hour session researching the complete history.

You can check out the current state of our program here:

Universe of Instrumentation Program

Edison Tech Center opens up new program site

In the beginning of 2016 the Edison Tech Center launched a new site “EdisonTC.org” to host new program content. Many of our older program pages will continue to operate undisturbed in our former static site, but newer content well be published under our new framework.

Giving our own volunteers a voice:

The effort to launch the new site is a response to the growing needs of our users who need a more responsive design for mobile and smaller screens.  A great new feature however will be to streamline the publishing process and empower our volunteers to contribute more material. Our content contributors hold a passion for engineering and history and we want to make it easier for them to express themselves and share the lifetimes of knowledge they have worked hard for.

More Readers Helping Readers:

In addition to internal improvements EdisonTC.org will allow users to interact and give useful comments under articles. We will continue to enforce a standard for comments similar to the BBC News website: There will be no offensive or personal attack language permitted and comments that are political or promote conspiracy theory or personality cults will be removed. Overall our goal is to engineers to help comment on topics and contribute towards other readers understanding of the topic, and possibly refer them to other good articles on the subject.

We’ve started the new site with our latest project on engineering tools called “Universe of Instrumentation”.  You can check out the new UI program here.

Thanks for reading and don’t forget to connect with us on Facebook or subscribe to our YouTube channel.


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