Regency TR-1

Last updated
Regency TR-1 transistor radio Regency TR-1.jpg
Regency TR-1 transistor radio

The Regency TR-1 was the first commercially manufactured transistor radio, introduced in 1954. Despite mediocre performance, about 150,000 units were sold, due to the novelty of its small size and portability. Previously, transistors had only been used in military or industrial applications, and the TR-1 demonstrated their utility for consumer electronics, offering a prescient glimpse of a future full of small, convenient hand-held devices that would develop into calculators, mobile phones, tablets and the like. Surviving specimens are sought out by collectors.

Contents

Regency TR1 schematic US2892931 Fig 1 Regency TR1 schematic .PNG
Regency TR1 schematic

Conception

Bell Labs invented the transistor in 1947. Despite its much smaller size and power usage compared to the vacuum tube, by 1954 the transistor had not replaced tubes in consumer electronics except in hearing aids, because of the new component's high cost of $20, compared to $1 for a tube. [1]

In May 1954, Texas Instruments (TI), previously a producer of instrumentation for the oil industry [2] and locating devices for the US Navy, wanted an established radio manufacturer to develop and market a radio using TI's transistors. No major radio maker, including RCA, Philco, and Emerson, was interested. Previous vacuum tube-based pocket radios had been unsuccessful; some companies made their own transistors and did not want to use TI's. Ed Tudor, the president of Industrial Development Engineering Associates, (I.D.E.A), a builder of home antenna boosters, jumped at the opportunity to manufacture the TR-1, predicting sales of the transistor radios would be "20 million radios in three years". Many Americans were building bomb shelters, and the company expected that they would want a pocket-sized radio for emergencies. [1] [3]

TI was not interested in manufacturing radios; its goal was to increase demand for its transistors so that the per-unit price would decrease from $10-15. The Regency division of I.D.E.A announced the TR-1 on October 18, 1954, and put it on sale in New York and Los Angeles on 1 November 1954. [2]

Design

The original TI prototype used eight transistors; when the company met with I.D.E.A. it used six. [2] The Regency TR-1 circuitry was refined from the TI design, reducing the number of parts, including two more expensive transistors. Although this severely reduced audio output volume, it let I.D.E.A. keep the price down to $49.95, ($510 in 2021), which was a significant amount of money for such a small, untried object. [4]

Aesthetics

I.D.E.A. outsourced the TR-1 exterior design to the industrial design firm of Painter, Teague and Petertil. [2] The design was created within six weeks by way of telephone and design sketches exchanged by mail. The design won an award from the Industrial Design Society of New York and was selected by the Museum of Modern Art for the American Art and Design Exhibition in Paris in 1955. [5]

The TR-1 was initially offered in black, bone white, mandarin red, and cloud gray, it was later uncommonly offered in olive green, mahogany, and eventually in rare colors including lavender, pearl white, turquoise, pink, and lime. It was advertised as measuring 3" × 5" × 1.25" (7.62 × 12.7 × 3.2 cm) and weighed 12 ounces (340 g) including the 22.5 volt battery. It came in a cardboard box with the color stamped on the end. An optional earphone sold for $7.50. [6]

The red triangles on the frequency dial mark the CONELRAD frequencies of 640 and 1240 kHz.

Technical design

The TR-1 uses TI's NPN transistors, hand-picked in sets of four. A 22.5 volt battery provides power, since the only way to get adequate radio frequency performance out of early transistors was to run them close to their collector-to-emitter breakdown voltage. The current drain from this battery is only 4 mA, [7] allowing 20 to 30 hours of operation, in comparison to only several hours for the portable receivers based on vacuum tubes. [8] The Regency TR-1 was patented [9] by Richard C. Koch, Project Engineer at I.D.E.A. [10]

Circuit

TR-1, circuit board and casing. Exhibit of Deutsches Museum, Munich Regency TR-1 opened front Deutsches Museum.jpg
TR-1, circuit board and casing. Exhibit of Deutsches Museum, Munich
22.5 Volt battery used in the Regency TR-1 (AA battery for comparison shown on left) 22,5Volt-AA-Battery.jpg
22.5 Volt battery used in the Regency TR-1 (AA battery for comparison shown on left)

The TR-1 is a superheterodyne receiver [2] [11] with four n-p-n germanium transistors and one diode. It contains a single transistor converter stage, followed by two intermediate-frequency amplifier stages. After detection, a single-transistor stage amplifies the audio frequency. All amplifier stages use common emitter amplifiers. Stages are transformer coupled, with tuned transformers for the intermediate frequency amplifiers and a miniature audio transformer for the loudspeaker. The intermediate frequency transformers are paired with capacitors, and hand tuned to the intermediate frequency (262 kHz [7] ) using movable cores.

The circuit was designed so as to get the maximum possible gain out of the first three transistors (which operated at radio frequencies). The first transistor used as a frequency converter was operated very close to its VCBO of 30 volts (from the 22.5 volt battery). This gives a larger depletion layer between the collector and the base which reduces the parasitic feedback due to the Miller effect and extends the frequency range. A lower voltage, however, will reduce the depletion layer width, increasing the collector-base feedback capacitance. This has an unusual effect. Because the IF strip is neutralised at the *expected* values of feedback capacitance, the TR-1 IF strip will break into oscillation at low battery voltages. On test, this occurred below about 16 volts. The two intermediate frequency amplifier transistors are neutralised to cancel out their parasitic Miller effect feedback which also extends their frequency range. Replacement transistors were supplied with the correct neutralising capacitor of 100-200 pF.

The receiver has automatic gain control. The DC level of the detected signal is filtered with a large capacitor and used to control the gain of the first IF stage. [12]

The 22.5 V battery, while now uncommon, is still used in some devices and as of 2020 remains available on the market. [13] The minimum required voltage is lower, about 15 V, below which the radio oscillates. An electrolytic capacitor is connected in parallel to the battery to improve stability. The power switch is coupled with the volume control.

Manufacture

Regency began assembling the TR-1 on October 25, 1954, supervising a collective effort by manufacturers around the United States. [6] [3]

Legacy

One year after the TR-1 release, sales approached 100,000 units. [14] While the radio was praised for design aesthetics, novelty and small size, because of the cost cutting measures, the sensitivity and sound quality were behind the established vacuum tube based competitors, and reviews were typically adverse. A review in Consumer Reports mentioned the high level of noise and instability on certain radio frequencies, and recommended against purchase, [8] stating that while listening to speech was "adequate", music quality was unacceptable. [2]

TI and I.D.E.A. did not disagree with the poor reviews, as they knew of the technical limitations resulting from only using four transistors. They did not know that Raytheon was working on a table radio using transistors; appearing in February 1955, the larger case allowed a design with six transistors, significantly improving sound quality. In August 1955 a small Japanese company released its first transistor radio, the TR-55; the company renamed itself Sony and became the world's dominant consumer radio manufacturer. [2]

See also

Related Research Articles

<span class="mw-page-title-main">Amplifier</span> Electronic device/component that increases the strength of a signal

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal. It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. An amplifier is defined as a circuit that has a power gain greater than one.

<span class="mw-page-title-main">Vacuum tube</span> Device that controls current between electrodes

A vacuum tube, electron tube, valve, or tube is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.

<span class="mw-page-title-main">Transistor radio</span> Portable radio receiver

A transistor radio is a small portable radio receiver that uses transistor-based circuitry. Previous portable radios used vacuum tubes, which were bulky, fragile, had a limited lifetime, consumed excessive power and required large heavy batteries. Following the invention of the transistor in 1947—which revolutionized the field of consumer electronics by introducing small but powerful, convenient hand-held devices—the Regency TR-1 was released in 1954 becoming the first commercial transistor radio. The mass-market success of the smaller and cheaper Sony TR-63, released in 1957, led to the transistor radio becoming the most popular electronic communication device of the 1960s and 1970s. Transistor radios are still commonly used as car radios. Billions of transistor radios are estimated to have been sold worldwide between the 1950s and 2012.

<span class="mw-page-title-main">Valve amplifier</span> Type of electronic amplifier

A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers in the 1960s and 1970s. Valve amplifiers can be used for applications such as guitar amplifiers, satellite transponders such as DirecTV and GPS, high quality stereo amplifiers, military applications and very high power radio and UHF television transmitters.

The Hartley oscillator is an electronic oscillator circuit in which the oscillation frequency is determined by a tuned circuit consisting of capacitors and inductors, that is, an LC oscillator. The circuit was invented in 1915 by American engineer Ralph Hartley. The distinguishing feature of the Hartley oscillator is that the tuned circuit consists of a single capacitor in parallel with two inductors in series, and the feedback signal needed for oscillation is taken from the center connection of the two inductors.

<span class="mw-page-title-main">Armstrong oscillator</span>

The Armstrong oscillator is an electronic oscillator circuit which uses an inductor and capacitor to generate an oscillation. The Meissner patent from 1913 describes a device for generating electrical vibrations, a radio transmitter used for on–off keying. Edwin Armstrong presented in 1915 some recent developments in the Audion receiver. His circuits improved radio frequency reception. Meissner used a Lieben-Reisz-Strauss tube, Armstrong used a de Forest Audion tube. Both circuits are sometimes called a tickler oscillator because the distinguishing feature is that the feedback signal needed to produce oscillations is magnetically coupled into the tank inductor by a "tickler coil" (L2, right). Assuming the coupling is weak but sufficient to sustain oscillation, the oscillation frequency f is determined primarily by the LC circuit and is approximately given by

<span class="mw-page-title-main">Push–pull output</span> Type of electronic circuit

A push–pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. This kind of amplifier can enhance both the load capacity and switching speed.

A Colpitts oscillator, invented in 1918 by Canadian-American engineer Edwin H. Colpitts using vacuum tubes, is one of a number of designs for LC oscillators, electronic oscillators that use a combination of inductors (L) and capacitors (C) to produce an oscillation at a certain frequency. The distinguishing feature of the Colpitts oscillator is that the feedback for the active device is taken from a voltage divider made of two capacitors in series across the inductor.

<span class="mw-page-title-main">Center tap</span> Contact made to a point halfway along a winding of a transformer or inductor

In electronics, a center tap (CT) is a contact made to a point halfway along a winding of a transformer or inductor, or along the element of a resistor or a potentiometer.

<span class="mw-page-title-main">All American Five</span> American radio with 5 vacuum tubes

The term All American Five is a colloquial name for mass-produced, superheterodyne radio receivers that used five vacuum tubes in their design. These radio sets were designed to receive amplitude modulation (AM) broadcasts in the medium wave band, and were manufactured in the United States from the mid-1930s until the early 1960s. By eliminating a power transformer, cost of the units was kept low; the same principle was later applied to television receivers. Variations in the design for lower cost, shortwave bands, better performance or special power supplies existed, although many sets used an identical set of vacuum tubes.

The Clapp oscillator or Gouriet oscillator is an LC electronic oscillator that uses a particular combination of an inductor and three capacitors to set the oscillator's frequency. LC oscillators use a transistor and a positive feedback network. The oscillator has good frequency stability.

<span class="mw-page-title-main">Electronic component</span> Discrete device in an electronic system

An electronic component is any basic discrete electronic device or physical entity part of an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not to be confused with electrical elements, which are conceptual abstractions representing idealized electronic components and elements. A datasheet for an electronic component is a technical document that provides detailed information about the component's specifications, characteristics, and performance. Discrete circuits are made of individual electronic components that only perform one function each as packaged, which are known as discrete components, although strictly the term discrete component refers to such a component with semiconductor material such as individual transistors.

In electronics, the Miller effect accounts for the increase in the equivalent input capacitance of an inverting voltage amplifier due to amplification of the effect of capacitance between the amplifier's input and output terminals, and is given by

In electronics, motorboating is a type of low frequency parasitic oscillation that sometimes occurs in audio and radio equipment and often manifests itself as a sound similar to an idling motorboat engine, a "put-put-put", in audio output from speakers or earphones. It is a problem encountered particularly in radio transceivers and older vacuum tube audio systems, guitar amplifiers, PA systems and is caused by some type of unwanted feedback in the circuit. The amplifying devices in audio and radio equipment are vulnerable to a variety of feedback problems, which can cause distinctive noise in the output. The term motorboating is applied to oscillations whose frequency is below the range of hearing, from 1 to 10 hertz, so the individual oscillations are heard as pulses. Sometimes the oscillations can even be seen visually as the woofer cones in speakers slowly moving in and out.

A valve audio amplifier (UK) or vacuum tube audio amplifier (US) is a valve amplifier used for sound reinforcement, sound recording and reproduction.

<span class="mw-page-title-main">Antique radio</span> Vintage telecommunication audio receiver

An antique radio is a radio receiving set that is collectible because of its age and rarity.

<span class="mw-page-title-main">Biasing</span> Background operating conditions for electronics

In electronics, biasing is the setting of DC operating conditions of an electronic component that processes time-varying signals. Many electronic devices, such as diodes, transistors and vacuum tubes, whose function is processing time-varying (AC) signals, also require a steady (DC) current or voltage at their terminals to operate correctly. This current or voltage is called bias. The AC signal applied to them is superposed on this DC bias current or voltage.

<span class="mw-page-title-main">Joule thief</span> Voltage booster electronic circuit

A joule thief is a minimalist self-oscillating voltage booster that is small, low-cost, and easy to build, typically used for driving small loads, such as driving an LED using a 1.5 volt battery. It can use nearly all of the energy in a single-cell electric battery, even far below the voltage where other circuits consider the battery fully discharged ; hence the name, which suggests the notion that the circuit is "stealing" energy or "joules" from the source – the term is a pun on "jewel thief".

This glossary of electrical and electronics engineering is a list of definitions of terms and concepts related specifically to electrical engineering and electronics engineering. For terms related to engineering in general, see Glossary of engineering.

In electronics, power amplifier classes are letter symbols applied to different power amplifier types. The class gives a broad indication of an amplifier's characteristics and performance. The first three classes are related to the time period that the active amplifier device is passing current, expressed as a fraction of the period of a signal waveform applied to the input. This metric is known as conduction angle (θ). A class A amplifier is conducting through all the period of the signal (θ=360°); Class B only for one-half the input period (θ=180°), class C for much less than half the input period (θ<180°). Class D amplifiers operate their output device in a switching manner; the fraction of the time that the device is conducting may be adjusted so a pulse-width modulation output can be obtained from the stage.

References

  1. 1 2 David Lane & Robert Lane (1994). Transistor Radios: A Collector's Encyclopedia and Price Guide . Wallace-Homestead Book Company. pp. 2–7. ISBN   0-87069-712-9.
  2. 1 2 3 4 5 6 7 Marsh, Allison (2024-09-30). "The First Transistor Radio: Engineering the Regency TR-1". IEEE Spectrum. Retrieved 2024-10-05.
  3. 1 2 Smicoe, Robert J. "The Revolution in Your Pocket". Invention & Technology Magazine, Fall 2004, Volume 20, Issue 2. Archived from the original on 2006-08-20. Retrieved 2010-04-20.
  4. ↑ Pies, Don (1998). "Regency TR-1 Transistor Radio History" . Retrieved 2019-02-19. and 140,000 TR-1's poured off the production line
  5. ↑ Handy, Erbe, Blackham, Antonier (1993). Made In Japan : Transistor Radios of the 1950s and 1960s. Chronicle Books. ISBN   0-8118-0271-X.{{cite book}}: CS1 maint: multiple names: authors list (link) pages 15–17
  6. 1 2 Reyer, Steve (Dr.) "Regency TR-1 Transistor Radio Facts and Figures". Retrieved December 2, 2012
  7. 1 2 TR-1, The First Transistor Radio Receiver. Technical Data And Service Notes. — Regency Div. I.D.E.A. Inc., Indianapolis, Ind., P. 2 Archived May 6, 2005, at the Wayback Machine
  8. 1 2 Schiffer, M. B. The portable radio in American life. — University of Arizona Press, 1991. — P. 170–178. — 259 p. — ISBN   9780816512843
  9. ↑ US 2892931,Koch, Richard C.,"Transistor radio apparatus",published 1959-06-30, assigned to I.D.E.A. Inc.
  10. ↑ Pies, Don (1998). "Regency TR-1 Transistor Radio History" . Retrieved 2019-02-19. Regency's master engineer, Dick Koch
  11. ↑ Regency schematic
  12. ↑ Lee, T. C. The Design of CMOS Radio-Frequency Integrated Circuits. — Cambridge University Press, 2004. — P. 271–272. — 797 p. — ISBN   9780521835398
  13. ↑ "Eveready 412 Carbon Zinc 22.5V Battery NEDA 215, 15F20, BLR122". Batteriesinaflash.com.
  14. ↑ Lane, David; Lane, Robert (1994). Transistor Radios: A Collector's Encyclopedia and Price Guide . Wallace-Homestead Book Company. ISBN   0-87069-712-9. page 4
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.