Your RF Cafe
April 1958 Radio-Electronics[Table of Contents]
These articles are scanned and OCRed from old editions of the Radio & Television News magazine. Here is a list of the Radio-Electronics articles I have already posted. All copyrights are hereby acknowledged.
Ooooh, I should have posted this story about 23 days ago, but better late than never. I meant to, but forgot. The story documents development of the "transistom" device back in the 1958 timeframe. Keep in mind that it was just a decade earlier that Mssrs. Bardeen, Brattain, and Shockley introduced the transistor amplifier to the world. The transistom was basically a 3-terminal transistor with two additional leads for a revolutionary power source built from radioisotopes of magnesium and manganese. In the day, school kids, including me, were handed blobs of liquid mercury to inspect and pass around in class, demonstrating how relatively ignorant we were about things we now consider to be extreme health hazards. Accordingly, encapsulating radioactive material in consumer devices was not a concern. The complete absence of transistoms in the marketplace today speaks volumes about its success.
This remarkable discovery foreshadows advances in two areas of the semiconductor field - diodes and transistors - and makes greater miniaturization possible while increasing transistor sensitivity. A radio battery with a life of 50 years is possible
By Mohammed Ulysses Fips, IRE*
Fips, you engineers are in the stone age," scowled the Big Boss, savagely biting his 7-inch Havana. "The idea of dry-cell- or house-current-powered receivers is not only preposterous, it's insane. Prehistoric, that's what it is! You yak all day long about your glorious science, my accomplished yaketeer - now come down to earth and compose. I'll give you 90 days to produce a receiver that needs no dry cells, no outside current - or else!"
A flashlight bulb is connected to the Transistom's atomic battery to demonstrate its power. The battery can keep the lamp lit for 50 years.
I soon hit upon the solution. Radio-activity was the answer! I took out my dusty old handbook on Primary and Secondary Batteries and soon found that in Volta's and later physicists' potentials-of-the-metal series, magnesium and manganese have respective voltages of +1.628 for Mg and +1.239 for Mn, or a theoretical. total of 2.867 volts.†
If, I reasoned, I made these two metals radioactive and used them as an atomic battery, I should get at least 2 1/2 volts per element. I accordingly secured a small quantity of manganese and magnesium and took them to the neighboring atomic research plant on Long Island, whose director I knew. He put the metal bits into the cyclotron and bombarded them atomically for a week.
Here I should call attention to the fact that my first experiments had quickly shown that pure metals alone would not work as an atomic battery. I had to use a magnesium as well as a manganese alloy of certain proportions, which for patent reasons I cannot divulge now. I can state, however, that the alloyed metals used were much heavier in each case than manganese (atomic weight 54.94) and magnesium (atomic weight 24.32).
After the samples were "cooked" atomically, I called for them. The tiny pieces had been placed in a thick lead box, although the director assured me that the quantity of the now radioactive metal was sufficiently small that all the pieces together were not more dangerous than a dozen radium-luminous wrist watch dials.
I must also report that before I took the manganese and magnesium pieces to the cyclotron I had welded the thin 1/8-inch metal squares together. This was easy because they were almost paper-thin. The final atomic battery thus consists of a 1/8 x 1/4-inch magnesium-manganese radioactive strip (Fig. 1). The finished battery gives a voltage of just over 2 1/2 under a light load. As the load increases, the voltage of course drops as in an ordinary dry cell. You might wonder how the atomic battery works with its two main elements welded together. The answer is no different than in a dry cell in which the zinc can and the depolarizer (manganese dioxide) are intimately connected by the electrolyte (sal ammoniac and zinc chloride), which is highly conductive. Or take a storage battery in which the positive and negative plates are immersed in a bath of dilute sulfuric acid, which you'd think would short-circuit the plates.
Naturally, in an atomic battery, the energy is not chemical as in a dry cell nor "stored" electricity as in a storage battery. The energy in an atomic battery comes from the gamma radiation, which is then converted electronically in the two metals. A current then flows from the manganese to the magnesium.
What is the useful life of an atomic battery? My calculations show that a conservative estimate is 40 to 50 years. With future refinements, the life expectancy should be much greater.
My next step, naturally, was to hook up my atomic cell to a transistor, thus making it possible to construct a small radio in which the batteries would take up practically no extra room. Curiously, too, I soon found out that the atomic radiation had a decided influence on a transistor; it enhanced its sensitivity surprisingly.
The final and successful version is shown diagrammatically in Fig. 2. Here we have a standard three-lead transistor to which the atomic battery has been joined. For a number of technical reasons, the battery elements should not physically contact the transistor elements, hence I use a thin ceramic separating film. (Other suitable insulators can be used.) ††
Fig. 1 - The battery consists of two small squares of radioactive metals - magnesium and manganese - welded together.
The transistor battery is now encapsuled, as is standard practice with all modern transistors. This results in a new electronic device which I call the Transistom (transistor plus atom). The transistom, as will be noted, has five leads - three transistor and two battery leads. These external battery leads can be interconnected as necessary in various circuits. In a six-transistor set we can even hook all the batteries up in series, giving us 15 working volts to drive a large speaker.
Needless to state, the coming transistom circuitry is endless and the nuisance of battery replacements will soon be a thing of the past.
Long before the 90-day time limit imposed upon me by the Chief, I walked into his office unannounced one morning. Out of my vest pocket I pulled a six-transistor receiver. If it hadn't been for the loudspeaker, the little set would have fitted into an ordinary matchbox - but the speaker made it 50% bigger.
I put it through its paces and, if I must say so myself, it worked - as the French would say - formidable. Bignose, for once, was enchanted as I opened the tiny lid, showing him the "works."
In the office with the all-highest there were also the science editor and the electronics editor. All three listened politely and interestedly to my technical description of my transistom. Then there was a long, thick silence accompanied by pointed headshaking.
Finally Bignose cleared his throat and snickered, "Fips, my boy, do you ever read the papers and do you know what goes on nowadays? Did you know that the word radiation is akin to pestilence all over the world today? What do you think would happen to us if we printed your transistom story? A radio set that gives off deadly radiation! Admittedly you - and we - know that it wouldn't hurt a fly, but what about the public? What about the Radiation Energy Commission (REC)? What about the National Health Service? People are hysterical today about any form of gamma radiation. You know that every kind of X-ray-except in doctors' hands - is taboo now. And now you want us to publicize a radio set that gives off gamma rays! Indeed!"
"Frank," this to the science editor, "bring in your Geiger counter!"
Frank returned in a minute with the Geiger and brought the probe to within a foot of my receiver. Of course it clicked furiously, as was to be expected - it would have done that with a luminous radium wristwatch dial, too.
"Look here, Fips," rasped Joe, the electronics editor, "can't you just visualize the ads of the large set manufacturers screaming 'Buy a safe NonRadiation battery set that won't endanger your or your family's health.' "
"Yes, Fips," piped in Frank, "you must know too that radiation today is the big political weapon of all our enemies and detractors the world over. Japan leads all Asia in bellowing at America to stop all forms of radiation and fallout to safeguard future generations. European scientists condemn us for the same reason.
"Kruschev, I am positive, would hop on your radiation radio as an excellent propaganda springboard to denounce our Western decadence and irresponsibility for foisting more misery and suffering on an already distressed world, all for the sake of our capitalistic dollar."
"No, Fips," this from the electronics editor, "I know what is in your mind - you want to encase your chassis in lead to stop all radiation. That, my boy, is no solution. Aside from the impossible added weight, think what a picnic the battery set manufacturers would have in their ads, telling service technicians to stay away from servicing dangerous radiation sets! Aside from this, shielded or not, your set would still be taboo - because of its potential radioactive danger. No, you'll have to start all over. I admit your scheme is brilliant - but with today's wholly uncalled for radiation hysteria, you must chart a new course."
Whipped and beaten down once more, I shuffled out the hallway. At the bend on the wall I glanced at the large leaf calendar and sadly noted the date:
*Institute Radioactive Engineering.
†A recent magnesium-carbon-manganese dry cell actually gives 2 1/4. volts.
††My latest transistoms now use light-gauge magnesium and manganese wires welded together.
Posted April 24, 2014