March 1956 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.
Radio-Electronics magazine editor Hugo Gernsback, 1955 marked the 50th
anniversary of "home radio." You would be excused for maybe thinking the world's
first home radio set was one of the early "tombstone" style tabletop radios in a
stylish wooden case, with a dial on the front for tuning one of the relatively
few (at the time) AM stations, and sometimes even shortwave. In actuality, it
the TELIMCO Wireless Telegraph Outfit; the only audio signal it emitted was
fixed tone indicating a dit or a dah. Music and speaking came a couple years
later. Pittsburgh radio station
KDKA* is famously the first commercial radio broadcaster, which began
operation in 1920.
Here are some KDKA articles:
Photographic History of Radiotelephony,
Half a Century of Electronics Publishing - 50th Anniversary,
New Antenna to Multiply Field,
Mac's Service Shop: How it Started,
Men Who Made Radio - Frank Conrad.
50 Years of Home Radio
Left - Advertisement for the first radio set offered the public.
It appeared in Scientific American, Jan. 13, 1906. Right - Picture diagram of layout,
drawn by Hugo Gernsback in the 1900's: A, G, antenna, ground; S, spark coil; B,
batteries; K, key; AS, relay adjusting spring; SD, coherer - Connections: 9, 8,
to relay electromagnets; 7, 11, coherer; 13, 16, decoherer; 14, 13, relay contacts.
Replicas of the original transmitter and receiver, soon being
sent to the Ford Museum at Dearborn.
Center - the receiver: A, antenna system; B, dry cell; C, coherer
; D, decoherer; P, adjustable coherer rods; R, 75-ohm relay.
Right - the transmitter: A, antenna and counterpoise; B, dry-cell
power supply; C, 1-inch spark coil; O, spark-ball oscillators; K, transmitter key.
By Hugo Gernsback
A half-century ago, the first radio for the public's use and enjoyment was marketed.
Differing vastly from today's radios in construction and function, it opened
the field of radio for private interest and amusement rather than commercial communications
The year 1955 marked the 50th anniversary of the first home radio sold to the
public anywhere in the world.
It was not radio as we know it today because in 1905 there was no commercial
broadcasting. But wireless had been going strong for several years and amateur radio
too had just begun. Marconi and other pioneers were transmitting intelligence by
the dot-and-dash method; indeed wireless in those days was rapidly forging ahead.
The public at large knew little or nothing about wireless before 1905, except
what they read in the papers and in magazines. As for owning a wireless home set,
it had not as yet been born.
Previous to 1905, in 1903-04, the writer had been working on a small portable
transmitter and receiving outfit which he felt could be sold to the public. It took
several years to perfect it and make it foolproof so it would work under practically
all conditions. It had to be low in cost so everyone could buy the outfit.
This ambition was realized some time in 1905. After making a number of models
the writer began to market the first home or private radio set ever sold to the
As there were few wireless stations in the country, it became necessary to sell
a transmitter, too, so amateurs could set up a transmitter and receiver at home.
Then while one person was transmitting signals, the other could receive them. Or
the transmitter could be set up in one room and the receiver would ring a bell in
the other room without any intervening wires whatsoever.
The outfit that accomplished all this was known as the TELIMCO Wireless Telegraph
Outfit. TELIMCO is a contraction of the first letters of the writer's old pioneer
firm, The Electro Importing Company (E. I. Co.), which became famous between 1904
and 1915 as the first radio mail-order house in the world. Only comparatively few
sets were sold in 1905. But in 1906 the little outfit went into quantity production
and was sold through many large outlets, including such famous stores as Macy's,
Gimbel's and F. A. O. Schwarz, the country's largest toy establishment.
Incidentally, it was first advertised in the magazine Scientific American in
the issue of Jan. 13, 1906. This was the first home radio set advertisement to appear
in print anywhere.
The writer well remembers the incredulous looks of many of the store owners when
they were first approached to buy "wireless sets." It was necessary to make a demonstration
in each case before anyone would stock them.
The complete set, both receiver and transmitter, at first was marketed for $7.50.
This was raised later on to $10, at which price most of them were sold.
The photograph shows an exact replica of the original outfit, built by the writer,
to commemorate the 50th anniversary of the first home radio set. The transmitter,
with the three dry cells and key, was composed of a 1-inch spark coil. The "1-inch"
here means that the coil threw a 1-inch spark through free air, between wire points.
Mounted on the spark coil, on two metal standards, were two brass oscillator balls
between which a small blue spark jumped the 1/8-inch gap. The spark coil had a fast
vibrator so that every time you depressed the key a spark would jump between the
two balls. Depressing the key for a short period would give a dot, a longer period
would give a dash.
The receiver was a 75-ohm "pony" relay which had to be so sensitive that if you
blew your breath slightly against the armature its contacts would close. There was
also a single dry cell and the all-important coherer. It was simply constructed
of two large, double binding posts through the bottom holes of which passed two
silver-plated brass rods. A glass tube, placed between the two binding posts, was
slipped over the two brass rods. These silver-plated 1/8-inch metal rods fitted
the glass so that there was extremely little or no play. The two rods were separated
about 3/16 inch, forming a gap. This gap was filled with the "soul of the set" -
the coherer filings, composed of 90% coarse iron and 10% coarse silver filings.
By shaking the mixture well it was ready to be used. The filings had always to be
loose, never packed tight.
The decoherer - an ordinary house bell - was mounted so that the clapper of the
bell would strike against the glass tube of the coherer at the exact spot where
the filings were. If the diagram is studied, it will be seen that every time the
relay closes its contacts, the bell will ring through the single cell.
Now, if you depress the key at the transmitter, the two aerials (aerial and counterpoise)
will emit radio waves. Curiously enough, the waves which the writer used 50 years
ago were of the very short variety (above 30 megacycles) to which modern radio has
come back. The two aerial wires of the transmitter measured less than 1 1/2 feet.
Inasmuch as the coherer is directly in the receiver aerial circuit, the filings
offer a very high resistance. But under the onslaught of the radio waves they instantly
become an excellent conductor - as if they now were a solid conductor. The relay,
in the same circuit, now goes into action, attracting the armature which closes
its contacts. This sets off the decoherer bell which rings and shakes up the coherer
filings. These now fly apart - they decohere - and the coherer becomes nonoperative
until the next wavetrain comes along.
Thus every time you press the transmitter key, the bell at the receiver rings.
It rings as long as you hold the key down. A long ring is a dash, a short one a
You can pick up the receiver and walk to· the next room, yet the bell sounds
without any visible connection. Even through thick walls, signals still come in.
One of the things that bedeviled us in the early days was sparking at the relay
contacts. This would set up electromagnetic waves and often the outfit gave no clear
signals; sometimes the bell would ring for seconds after the signal. This was overcome
by putting a 5-μf capacitor across the relay points.
The range of the TELIMCO Wireless Telegraph Outfit was between 300 to 500 feet
when used without ground connections. By using an elevated aerial 50 to 100 feet
in length and by grounding one side of both transmitter and receiver to a water
or gas pipe, the range was easily increased to one mile. Indeed, hundreds of people
who bought the outfit at the time reported excellent reception even over greater
distances, but these, of course, were exceptions. Note that this set used no tuning
A curious thing about this little outfit today is its strange effect on radio
people who never heard of the ancient spark coil and coherer sets. Young radiomen,
who have never seen one of these outfits, are usually very much perturbed and astonished
when the writer demonstrates it. The reason of course is that people have difficulty
realizing that with a little three-dry-cell transmitter it is possible to ring a
bell through intervening walls while the novice holding the receiver.
Radiomen today think of devices which operate relays as being relatively large
and find it hard to believe that such a small portable transmitter and receiver
could do the work.
It is conceivable that some time in the future these same instrumentalities may
still find a use in modern radio and electronics which may not be apparent today.
The TELIMCO outfit here described has recently been acquired by the Henry Ford
Museum of Dearborn, Mich. It was donated by the writer. It will be permanently exhibited
in the radio section of the museum.
Posted October 13, 2022