(Photo created with AI assistance may not physically resemble apparatus actually made)
I want to narrate here an episode in my professional life as
an electronic equipment designer and also a businessman. I think that this
episode is rather noteworthy, because sometimes projects need to be taken up
even when it is known that it is an outright wrong business-wise decision. In
this case, the technical excellence and elegance of an idea won over the value
of business and profit margins.
Sometimes in early 1970’s, I received a letter from Mr.
Gadgil, our dealer in Mumbai. The contents were rather unusual. According to
him, Physics Department of University of Bombay had recently included at that
time, a new experiment in the “Practicals” curriculum for the B Sc. Degree
course in Physics. This experiment was
described as, ‘e/m of an electron using a magic eye indicator’. Mr. Gadgil had further added that he had made
enquiries with colleges and other traders. Unfortunately, no one in the Physics
departments of affiliated colleges knew anything about this experiment.
Similarly, no scientific instrument manufacturer in India was making any such
apparatus with which this experiment can be carried out. E/m of
an electron is a physical constant with a value 
Coulombs per kilogram.
After reading this letter, my first reaction was to find out
whether to spend resources on such unknown product would make any business
sense or not? I wrote to Mr. Gadgil
regarding the possible purchase price of a suitable apparatus that the colleges
may afford and would be willing to buy.
And what would be total volume of the possible business? After a few days, Mr. Gadgil gave me rough
indications for both these, which I found ridiculously low, almost a
pittance! At that time there were only
26 affiliated colleges with University of Bombay offering a degree in Physics.
All of which were unlikely to buy this new apparatus. Besides this, no other University in India
had included this experiment in their Physics degree curriculum till then. From
any consideration, this was an outright wrong decision to waste time over this
project, and I informed Mr. Gadgil accordingly.
Surprisingly, things did not end here. In one of our
meetings later, Mr. Gadgil kept on pursuing me to manufacture a suitable
apparatus for this experiment, as colleges kept on pressurizing him to help
them out. Finally, I gave in. I told Mr. Gadgil that I would try to manufacture
a suitable apparatus, if he was ready to invest some amount and give me an initial
order for at least 15 Nos at a price to be negotiated later.
Rather reluctantly, I started giving some thoughts to
project. To start with there were two problems. Firstly, I had to find the
original article where this experiment was explained. The second difficulty was
about the magic eye tube. Since we had an old Westinghouse radio in the house
that incorporated this tube, I knew at least how it looks. By 1970’s, even
though valve radio sets were still common, transistor radio sets were available
in market and were getting popular. The valve radios available in market still
used these magic eye tubes as tuning indicators, but they were of different
types. In this type, two green strips would be seen moving towards or away from
each other. When a station was tuned, the green strips would move towards each
other or even meet. This tube was called type EM80 and it was of original PHILIPS
design but made in India by Bharat Electronics
Ltd. . Availability of this tube was of no use to me as what I needed was a
valve with round display at top. This display was in form of a segment of a green
donut or a butterfly like ring and when a station was tuned, the ends of the green butterfly wings would
appear to close and would form a donut like green ring. Such valves were used earlier in 1940’s and
1950’s and were made by American companies like RCA with type numbers such as
6E5 or 6U5. These magic eye indicators were no longer being used in Radio sets
in India.
(Type EM 80 Magic eye tuning indicator, available but not useful)
{Image source By Gvogia - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22609210}
( RCA 6E5 magic eye tuning indicator, what was required)
{Image source By Poc, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12456463}
During my next trip to Mumbai I went around Lamington Road
Electronic markets, looking for 6E5 or 6U5 tubes. RCA tubes were difficult to get;
it was possible to get some other east European make at reasonable cost. This
was positive news for me. Yet the main
obstacle was still to be overcome.
Details of this experiment for which an apparatus was to be built were
still unknown. Despite my best effort, I was unable to find any reference to
this experiment in any book or journal in two well-known Libraries in Pune,
those of Poona University and College of Engineering. Finally, I contacted Mr.
Gadgil again and told him to go and meet Professor of Physics at the University
of Bombay and try to find out any information, if available with him.
Mr. Gadgil met the concerned professor in the university,
which had now shifted to ‘Kalina’ near Santa Cruz suburb of Mumbai and managed
to get reference to an article in some publication about this experiment. Once
I had this information, I soon managed to get a photocopy of this article. However,
I do not now remember this article or where it was published. While writing this blogpost I made extensive
search on net but did not produce any positive result. Surprisingly I found
that this experiment is now described in number of articles published in last
10/15 years and there are even a few You Tube videos made on it. Yet the
original article is not mentioned or referred to anywhere and is unfortunately lost
forever.
With this information in hand, I started to make a prototype
and soon succeeded. In about two weeks’
time, our finished apparatus was ready. Without going into any theory or
practicalities I can describe the apparatus here (See the image also) in
this way. It consisted of a sheet metal box painted in nice ivory colour which housed several power supplies. A coil of copper wire wound on a bobbin was
fixed on top of the box. A standard octal valve socket was also fitted on the
box so that the magic eye tube could be fitted inside the core tube of the
bobbin. Screw type terminals were provided for connecting voltmeters and
ammeters. A potentiometer control was provided for adjusting grid volage. A mains power on off switch and a power
indicator also were provided. A
measurement template also was made, which could be placed on top of the coil.
Having finished the apparatus, I sent it to Mumbai for
practical demonstrations in various colleges. Within a month Mr. Gadgil happily
confirmed that the demonstration went well and value of e/m measured by
colleges with my apparatus came right always quite accurately. A few colleges had
already placed orders, and we should start manufacturing as soon as possible.
I was happy with the result, yet businessman in me was not
particularly enthused as the order quantity and the price realized were quite
low. Yet I resigned myself to the thought that the work was sort of promotion
for us, like giving diaries or Diwali gifts. Soon the order was completed and
matter closed. We never made this product again.
I could, however, never understood, Bombay University’s
logic in introducing this experiment in curriculum without ensuring that the
key component to make the experiment apparatus is available and was no longer
manufactured.
10th December 2025
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