Paperthin Radio
April 1960 Radio-Electronics

April 1960 Radio-Electronics [Table of Contents] Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

In this April 1960 Radio-Electronics magazine article by the fictitious electronics wizard Mohammed Ulysses Fips (a Hugo Gernsback pseudonym), the narrator presents the "Paperthin Radio" - an ultra-thin, lightweight transistor radio designed to undercut Japanese competition. Built on a stiff paperboard chassis just 1/16-inch thick, the radio uses standard components cemented into place, with conductive ink for wiring. Key innovations include a flat ferrite-loop antenna, a modified trimmer capacitor for tuning, and the "Leptospeaker" - a slim electromagnetic speaker using an Alnico disc magnet. The two-transistor circuit delivers adequate reception for urban areas, with mass-production costs estimated at $2-$3 per unit. The narrator's boss, however, erupts in fury, condemning the design as a threat to the servicing industry and manufacturer profits, culminating in a violent outburst - revealed to be an April Fools' prank when the radio announces the date: April 1st. The piece satirizes industry anxieties over disposable electronics and foreign competition.

Paperthin Radio - 2-Transistor Receiver on a Stiff Sheet of Paper

By Mohammed Ulysses Fips, IRE*

When the big boss called me into his august presence that blizzardy morning, the air was surcharged not only outside but in his office, too. There was a distinct high-tension charge in the air as the scowling big man waved me into a chair without a word.

He was puffing on a big, six-inch Havana Morona that jutted out into space at an ugly angle of 45° - always a sure sign that all was not well.

For a while he contemplated me silently, as if I were some loathsome transgalactic bug. Finally, he yanked the well-chewed cigar from underneath his big proboscis, rasped his throat and croaked:

"Fips, what in tarnation am I paying you a salary for here? You are supposed to be the new-idea boy on this magazine; instead you are the no-idea man.

When, in a weak moment, I took you back after I fired you last year, I hoped that you had reformed and buckled down to work. Instead, your head is the same old vacuum - not an idea in your cranium!

"Have you any conception of what goes on in today's electronic world?

Here, the Japanese are drowning us in transistors and transistor radios. If you read the papers, you will have learned that in 1959 Japan made 50% of all the transistors used in the US. Soon they will make all our radios - indeed, this year their first transistor TV's will begin inundating us. What next? And what are we doing to stem that tide? Where is our superior American know-how? What have YOU to offer in our hour of need?"

"Boss," I said in my most ingratiating tones, "I have just the thing you want. I have been working on it for a year - a radio that can be completely mass-produced by automation, hence can be made cheaper than Japanese sets. It is also the lightest, slimmest radio in the world. Yes, we can even export it to Japan!"

For a moment the boss was speechless, but incredulous.

"When can you show me a sample?" he demanded gruffly.

"I will have it in exactly one week from today," I promised. "And you will be delighted with it. You'll scoop the world."

For quite a while I had been working on my new and revolutionary radio, but it took me many months to iron out the bugs.

My latest model is a stiff, white paperboard, the usual artist's drawing board. It measures 5 inches by 6 inches, but can easily be made the size of a postal card, 5 1/2 inches by 3 1/4 inches, when mass-produced. Its thickness is about 1/16 inch for the board part. None of the components project more than 1/8 inch above the holding surface, hence the Paperthin Radio is the thinnest in the world. It is also the lightest.

The model I describe here is made of a stiff paperboard. In mass production, the chassis can be made of plastic, fiber or other insulator.

All components are set in the paper chassis and cemented in place permanently - half the component juts out on one side, half on the other. All the wiring is traced in the usual conducting ink. For large-scale production, standard method printed-circuit techniques will be used.

The antenna is a flat, thin strip of ferrite wound with about 100 turns of No. 30 enamel wire. It is cemented in a tight-fitting rectangular hole in the paper chassis. All fixed capacitors and resistors, transformer, batteries, etc., are standard makes and are cemented in holes in like manner.

The tuning capacitor is a standard 3/4 x 5/8-inch trimmer. Normally this has a capacitance of 3 to 40 μμf. This is not sufficient for broadcast tuning range, as a minimum of 360 μμf is needed. To increase the capacitance, I removed the 0.06-cm-thick mica insulator and substituted a 0.005-cm piece of special high-dielectric polykap plastic film.† This combination gives a little over 360 μμf.

A short length of brass rod is soldered to the adjusting screw to replace the usual tuning knob, which would take up too much room. To insulate the handle, a short piece of soft-plastic tubing is slipped over it.

Now for the loudspeaker. This was the most troublesome component, because no thin electromagnetic loudspeaker is commercially available; none has ever been made. The detailed illustration explains its construction as conceived by me.

Because of its slimness, I named it the Leptospeaker (Lepto, from the Greek, thin.) Its main part is an Alnico disc 2 1/8 inches in diameter 1/16 inch thick. It is magnetized in such a way that one pole forms the center part of the disc; the other pole is located around the rim. In the center is a soft-iron pole piece 1/16 inch high by 1/4 inch in diameter. On this is wound a magnet coil of No. 38 or 39 enameled copper wire to the approximate impedance of 500 ohms.

This assembly is fastened with a special epoxy cement over a 1 7/8-inch hole in the paperboard chassis. On the other side of the hole there is fastened with epoxy cement a standard 2 1/8-inch iron telephone diaphragm.

The arrangement makes an excellent loudspeaker that requires no baffle, because the stiff paperboard acts as its own baffle. As the chassis is only about 1/16 inch thick, the vibrating speaker diaphragm is sufficiently distant from the pole piece so that it cannot touch it. (Note: The chassis cannot be too thin or the diaphragm will touch the pole piece and rattle.)

The two transistors are cemented flat into two holes cut into the chassis, one half protruding on one side, the other on the back side.

The same procedure is used with the batteries; flat spring clips for contacts are provided on both sides of the chassis - this assures positive connections.

For simplicity, one of the battery spring clips is mounted on a washer and riveted to the chassis. Moving the clip sideways breaks contact. This becomes the off and on switch.

The two-transistor circuit, as well as a parts list, used for the paperthin radio are given here. This receiver is excellent for city and suburban purposes. Extra transistors can, of course, be used with different circuits to increase range and output - but then the cost, too, goes up.

To increase the volume, the paperthin radio can be placed on a resonant wooden box. Ordinarily it can be placed at an angle on a simple wire frame, on a table or shelf. It needs no enclosure.

After the receiver has been tested, it should be sprayed on both sides with a plastic film to keep out moisture and dirt. When mass-produced, both sides will be covered with a tight-fitting, stiff plastic contour film (called "blister packaging"). Note: Tuning handle, off-and-on switch, loudspeaker diaphragm are not covered with blister packaging.

True to my promise, a week after our meeting, I marched into the boss' office and placed my brainchild on his desk. I switched it on and, if I must say so in all modesty, it performed beautifully, bringing in at least six stations at full loudspeaker volume.

The big boss, scowling ferociously, picked it up, turned it around and put it through its paces himself.

"And what do you call this contraption?" he bellowed.

Somewhat taken aback, I said: "This is the world's thinnest, lightest and perhaps the lowest priced paperthin radio ever invented."

"So," said he in his bossy voice, "and how much do you figure its cost if made by the million?"

"About $2 or $3. It could easily be sold for $4 or $5 at a good profit."

"And who would buy such a gadget?" growled the boss editor.

"Why, everybody, of course, and particularly children!"

"Great," spat out the Big Man. "And now tell me how do you repair such a toy?"

"Repair it?" I answered with some surprise. "The paperthin radio is so well constructed, it rarely needs repair. If it does, throw it away and get a new one - it's that cheap!"

"Hah, hah, hah," exploded the chief, his neck swelling a purplish red. "That's all I wanted to know! Here we publish a respectable magazine that's supposed to uplift our industry and lead it. Then you ... you infernal idiot, come along with a toylike thingumajig that will be sold for next to nothing so at the end of the year our set manufacturers will have built 20,000,000 of your phantom radios and will have made less profit than they make building 1,000,000 decent radios. On top of that, they must invest tens of millions of dollars in automation machinery, which they may not get back in 10 years!

"Worse, yet," he shrieked in an apoplectic rage, "a high percentage of our readers are service technicians, who make their living repairing sets in this country. Has it occurred to your evacuated brain how the servicing industry will receive the news of your radiotic invention? They'll boycott us for life and the radio-electronic industry will bury us, you ... you disgustingly stupid copy of a destructive and undermining termite - get out, OUT, and stay out!"

With that, the infuriated boss hurled my radio at me with such force that it would have smashed any receiver ever made.

Not mine. Luckily, I caught it and ducked out of the office at top speed. Somehow, in catching it, the on switch closed. As it was exactly 11 am, Station WROT came on. Before I turned it off, the announcer had said: "Here is the news on

April 1st"

* Institute Radio Electronology.

† Not available commercially as yet.