Category Archives: Telephone history

1948 Speaker Phone

1948JanPM11948JanPM2Today, most telephones, either landline or mobile, contain a speaker phone function, but this hasn’t always been the case. Shown here from 70 years ago is a very early version, the Jordaphone, shown here in the January 1948 issue of Popular Mechanics. The article notes that groups could now sit in on meetings without individual telephones with the instrument that “looks like a console radio.”

The article also stressed one important fact, that the Jordaphone “is not actually connected with the telephone line.” As those of us who grew up in the 1960’s and earlier are aware, the telephone line and “the instrument” were sacred, they were property of Ma Bell, and that tapping into the line was absolutely forbidden.

This device had a workaround. The telephone handset was set in a cradle in the top, and inductively coupled to the Jordaphone.



1957 Boys’ Life Telephone Circuit

1957NovBL1Sixty years ago, Maurice Peacock, Jr., of Radnor, PA, got $5 for sending these simple circuits to the “Hobby Hows” editor of Boys’ Life, where they were printed in the November 1957 issue.

The circuit shows how to rig up a telephone system to a friend’s house nearby, using an old radio headphone. One earpiece is used at each end, with batteries wired in series. Peacock explains that the wire needs to be insulated, and suggests that old thread spools can be used as insulators. The basic circuit is shown in figure 1. To save on the cost of wire, a good ground can be used as the return, as shown in figure 2.

I suspect the Boy Scouts of 1957 eventually figured it out, but the diagrams shown here wouldn’t work. A minor change needs to be made.

I suspect that, just like the Boy Scouts of 1957, our readers will quickly spot the problem. When you’ve found it, please comment on our Facebook page.



1942 Army Signal Corps Recruiting

1942NovPMThis recruiting ad for the U.S. Army Signal Corps appeared in Popular Mechanics 75 years ago this month, November 1942. It noted that this was a radio war, and that the nerve center of the army needed skilled hands.  It suggested a number of opportunities to serve.

Physically fit men ages 18 to 45 were eligible for direct enlistment in the Signal Corps Enlisted Reserve.  Those with experience as a licensed radio operator, a trained repairman, or active telephone or telegraph worker would qualify for active duty at once with pay of up to $138 per month, plus board, shelter, and uniforms.

Those without direct experience but “skilled with tools” would qualify for training and ordered to active duty after completing the course.

Degreed electrical engineers, as well as junior and seniors in EE programs, would be eligible for commission.

Young men over 16 having an ability with tools would be eligible for immediate training, with pay of not less than $1020 per year.  Even those with a minor physical handicap could find a place to serve.



1932 Church Group Hearing Aid

Group hearing aid receiver in use.

Group hearing aid receiver in use.

Today, almost every auditorium of any description is wired for sound, and we take for granted that someone will turn on the PA, and we’ll be able to hear what’s going on through the ubiquitous speakers.

But this hasn’t always been the case. We take the presence of the sound system for granted. But until the early 20th century, there was an absolute prerequisite for orators of any type: They needed to have a loud voice in order to be heard.

This was particularly true of churches. There was one qualification for ministers that was even more important then their theological bona fides: They had to be loud, since their sermon had to fill the sanctuary on its own power, without the aid of any electrical amplification.

This began to change in the 1920’s and 1930’s, as the “sound man” became an important player in the field of electronics. Wiring halls of any type for sound became a lucrative profession. And with the advent of the microphone, amplifier, and loudspeaker, the sheer volume of the preacher’s voice became less and less of an issue.

A related issue was addressed by an article appearing 85 years ago this month in the March 1932 issue of Radio News. Electronic amplification could solve another problem, namely allowing those with poor hearing to fully participate in church services and other public events. Personal hearing aids worked well for conversation with another person nearby. But they were largely useless for picking up a speaker at the other end of a large auditorium. For that reason, churches and other public venues were beginning to wire what the article called “group hearing aids,” or what we would today call assistive listening devices.

1932MarRadioNewsSchematicAs seen from the schematic here, the circuit is quite straightforward. A microphone is placed near the pulpit, is amplified, and is then fed to telephone receivers with individual volume controls.

The article concluded by noting that the date was not far distant when those with defective hearing would be able to walk confidently into any hall or meeting place knowing that provision had been made for them to participate fully in one more phase of well-rounded living.

Modern assistive listening devices (ALD’s) are typically wireless, most frequently operating below the FM broadcast band at 72-76 MHz. You can read more about modern systems at my ALD receiver page.



Carbon Button Microphone Amplifier

CarbonMicrophoneAmp

While they were rarely used in radio applications, the diagram here shows how a carbon button microphone amplifier could be used to drive a loudspeaker from a crystal set. This diagram is from 90 years ago, and appeared in the 1927 British Radio Year-Book.  The diagram actually appears in the advertisement for a book entitled Successful Crystal and One Valve Circuits by J.H. Watkins, who according to the ad was the wireless correspondent for the Daily Express.

The principle behind the circuit is very simple and almost self-explanatory.  The audio from the crystal set or other low-level source is fed to the traditional earphone.  A carbon button microphone is in physical contact with the earphone, and produces a stronger AF signal.  In this case, this stage is able to drive a loudspeaker.

This idea was rarely used in radio, since a vacuum tube amplifier provided better results and little additional cost.  The carbon button amplifier was more commonly used in telephone circuits, where they were the only method of amplification available prior to the vacuum tube.  They made long distance telephony possible.  They did have the advantage of a smaller size than a vacuum tube, and required less battery power.  Therefore, they did remain in use in hearing aids until the advent of the transistor three decades later.  You can read more about the carbon button amplifier at this site.

The advantage for the home constructor was probably cost, since driving a speaker this way would not require an expensive vacuum tube.  In fact, the carbon button amplifier could probably be constructed at home, which would be impossible in the case of a vacuum tube.  Students looking for a very novel science fair project might consider making one, since it would be possible to produce loudspeaker volume with entirely homemade components.



1917 Career Advice for Scouts: Electrical Engineering

1917FebBL

A hundred years ago this month, the February 1917 issue of Boys’ Life gave some career advice to scouts who were busy working on the Electricity merit badge, by letting them know how they could become electrical engineers.

The railroads, for example, relied upon telephone and telegraph systems and power plants. The “untrained man” could start as a conductor or motorman, but would remain in the ranks of the unskilled unlesss he added to his limited daily experience by a course of study in an area such as electrical engineering.

Such study could be done through private study and reading and correspondence and night schools, as well as more formal trade and engineering schools. Even the poor boy was not necessarily barred, since the best schools were often not the most expensive.

The article noted that getting ahead after graduation meant hard, dogged work, since the graduate still had to learn many practical engineering skills to get his bearings. But there was no reason why a competent technical graduate wouldn’t be able to rise to $2000 per year.

It should be noted that the magazine’s proofreader apparently let one slip by. The Morse Code shown in the illustration reads, “BE PREPARED AND DO A GOOD TURN DAMLY.”



Answer to Yesterday’s Quiz

1956DecQuistQuizA

Yesterday, we presented the problem of how to hook up a telephone to talk across a river from Point A to Point B, without running a wire across the river.

Loyal readers knew the answer right away, because we presented a similar system for a 1940 wireless telegraph using four ground rods.  Each side of the circuit was connected to two ground rods.  The January 1957 issue of QST shows a similar arrangement for how the two Boy Scouts could hook up their field telephone:

1957JanQuistQuiz2

Each telephone is hooked up to two ground rods.  The magazine suggests separating them by 20 times the width of the river (2000 feet).  There’s still a high resistance path between the two telephones, but the leakage resistance between A and A’ and between B and B’ is even higher.  The 1940 wireless telegraph, because it used an audio amplifier, could probably get by with less separation between the ground rods on each side of the river.  But with 2000 feet separation, the scouts’ telephones should work just fine, despite not being able to run any wire across the river.



Boy Scout Field Telephone-Telegraph, 1937

1937JanBLEighty years ago this month, the January 1937 issue of Boys’ Life carried this ad for the official BSA field set, a field telephone and telegraph.  For $9.50, a scout could acquire two such units.  The possibilities for use during hiking and camping, or between two friends’ houses, seem limitless.

More details are given in an ad appearing in the February 1934 issue, which reveals that the set is manufactured by the American Electric Company, of 1033 West Van Buren Street, Chicago, “one of the world’s foremost makers of commercial telephone equipment.”  Contained in a durable khaki colored weatherproof case having a strong carrying strap, the set was ready for use at any time by simply connecting to line wires.  The set was said to have a range to be able to signal and talk clearly over a thousand feet.  The set was switched from telephone to telegraph simply by switching the key into the telegraph position.

The set was patented under US Patent 2072264, which described the set as being “inexpensively and ruggedly built to fill the need for such an assembly by Boy Scout organizations and others having need for inexpensive equipment which may be employed to establish temporary or permanent telephone-telegraph communication between two points.”

The only evidence of a surviving example I was able to find online was this eBay listing, which unfortunately contains only a photo of the unit in the closed position.

A resourceful Boy Scout owning such a telephone probably wouldn’t have had much trouble figuring out the Quist Quiz which appeared in the December 1956 issue of QST:

1956DecQuistQuiz

Two Scouts, one on each side of the river, are equipped with their official BSA field telephone-telegraph sets.  Without crossing the river or running a wire across the river, how can they hook up the phones?

Loyal readers of OneTubeRadio.com already know the answer, since we previously showed a similar system.  If you missed it, you’ll need to wait until tomorrow to see the answer.



1936 Inter-Office Intercom

1936decradioretailingCallers to this 1936 factory were never asked to hold the wire. With this intercom from Sound Systems, this efficient information clerk was able to reach anyone in the plant instantly. The photo appeared in the December 1936 issue of Radio Retailing, which reminded readers that inter-office communication systems saved footsteps and sped up routine.



 

1941 Chicago Talking Juke Box

1941TalkingJukebox

Seventy-five years ago today, the Chicago Tribune, August 7, 1941, offered an interestingly candid look at the juke box industry in Chicago. Typically, a juke box would contain 20 records, and the patron put in a nickel in exchange for playing one of them.

Things changed when the K.P. Music corporation of 1057 Wilson Avenue came along with talking juke boxes known as “automatic hostesses.” Instead of twenty records, the patron had a choice of 680 records.  When the patron inserted his coins, he was connected, via leased telephone line, to a hostess at 1057 Wilson Avenue, with whom he could exchange banter, make a request, and even dedicate a particular number to his friends.

Eighteen taverns quickly signed up and junked their old jukes. This went over well with everyone, with one exception, and that was Michael J. Boyle, also known as the “Umbrella Man,” the head of the Electrical Workers’ union. He had two objections. He first argued that the new jukes were too good, and that hundreds of traditional juke boxes were in other taverns, with hundreds of dollars tied up. The new talking juke boxes would cut in too heavily, making the investment a “dead loss.”

Umbrella Mike got his name from his practice of hanging an umbrella from the bar when making a visit.  The owner of the tavern could then conveniently deposit an envelope into the umbrella so that Mike could be on his way with a minimum of fuss.

The old machines were serviced by, and more importantly, in the territory “belonging to” the Apex Cigaret Company of 4220 Lincoln Avenue. Depiste the name, Apex wasn’t in the cigarette business. Its business was juke boxes.

The newspaper identified Joseph “Gimp” Mahoney as the nominal president of Apex, “but Eddie Vogel, old time Capone gangster, is known as the power behind it. Those gentlemen’s relations with Mr. Boyle are cordial.”

To express their displeasure, the union’s business agent, along with about a half dozen members of the union, showed up at the 18 bars in question. They carried signs announcing that the talking jukes were “unfair to organized labor.” After picketing for a bit, the business agent would slip inside and unplug the machine. He also left some advice to the owners that “it was in their best interests that the boxes remain silent.”

Eleven of the 18 taverns took the advice, but at seven others, “the tavern owners showed the agent the door and the talking jukes went on talking.”

The newspaper reporter visited the talking jukebox studio and described the operation. The “hostess,” Miss Mickie Martin, shown above at the microphone, would be signaled by a light that some business was coming in from one of the taverns. Another indicator would show how many nickels had been fed in. Confirming that payment had been received, she would flip the switch and say sweetly, “hello, what can I do for you?”

The reporter noted that many voices would come over the wire, both old and new. “Some were those of strangers, some those of old friends who’d built up an acquaintance thru many nickels with Mickie.”

In one case, the connection was interrupted, and Mickie advised that they were having trouble at that establishment, since the business agent was there.

The firm’s attorney was dispatched to the bar in question, but by the time he arrived, the agent had pulled the plug and left the scene. The attorney lamented, “I’ve got 17 cousins on the police force, but what can you do when you run up against this kind of stuff?”

And not insignificantly, the old juke boxes were serviced by members of his own union.

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