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

In May 1954, Texas Instruments, previously a producer of instrumentation for the oil industry and locating devices for the US Navy, was looking for an established radio manufacturer to develop and market a radio using their transistors. No major radio maker, including RCA, Philco, and Emerson, was interested. 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." [1] [2]

The Regency Division of I.D.E.A announced the TR-1 on October 18, 1954, and put it on sale in November 1954.

Design

The Regency TR-1 circuitry was refined from the Texas Instruments drawings, reducing the number of parts, including two expensive transistors. Although this severely reduced audio output volume, it let I.D.E.A. keep the price down to $49.95, ($443 in 2016), which was a significant amount of money for such a small, untried object. [3] One year after the TR-1 release, sales approached 100,000 units. [4] 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. [5]

Aesthetics

I.D.E.A. outsourced the TR-1 exterior design to the industrial design firm of Painter, Teague and Petertil. 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. [6]

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. [7]

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

Technical design

The TR-1 uses Texas Instruments' 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, [8] allowing 20 to 30 hours of operation, in comparison to only several hours for the portable receivers based on vacuum tubes. [5] The Regency TR-1 is patented by Richard C. Koch, US 2892931  , former Project Engineer of I.D.E.A. [9]

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 made [10] 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 [8] ) 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. 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. [11]

The 22.5 V battery, while now uncommon, is still used in some devices and as of 2020 remains available on the market. [12] 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 TR-1s on October 25, 1954, supervising a collective effort by manufacturers around the country. The transistors and transformers came from Texas Instruments in Dallas. Capacitors came from International Electronics, Inc. of Nashville, [2] Erie Electronics of Erie, Pennsylvania, and Centralab of Milwaukee, Wisconsin. The speakers came from Jensen in Chicago, Illinois. IF transformers came from Vokar of Dexter, Michigan. The volume control came from the Chicago Telephone Supply in Elkhart, Indiana. The tuning capacitor came from Radio Condenser Co. in Camden, New Jersey. The Richardson Company in Melrose Park, Illinois and Indianapolis supplied the circuit board material to Joseph B. Weaver, founder of Photos by Weaver/I.D.E.A./Regency Electronics/Printed Writing, Inc., that manufactured the first circuit board in the basement of his home in Fishers, IN. The actual plastic case for the TR-1 was produced by Argus Plastics in Indianapolis, Indiana. [7]

Related Research Articles

Amplifier Electronic device

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power 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 a circuit that has a power gain greater than one.

Superheterodyne receiver Common type of radio receiver that shifts the received signal to an easily-processed intermediate frequency

A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to be invented by US engineer, Edwin Armstrong but after some controversy the patent is now credited to French radio engineer and radio manufacturer Lucien Lèvy. Virtually all modern radio receivers use the superheterodyne principle.

Switched-mode power supply Widely used type of power supply used to power electronic devices

A switched-mode power supply is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a DC or AC source to DC loads, such as a personal computer, while converting voltage and current characteristics. Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. A hypothetical ideal switched-mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power conversion efficiency is an important advantage of a switched-mode power supply. Switched-mode power supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight.

Transistor radio Portable radio receiver

A transistor radio is a small portable radio receiver that uses transistor-based circuitry, which revolutionized the field of consumer electronics by introducing small but powerful, convenient hand-held devices.

Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic. It is called so because the logic gating function is performed by a diode network and the amplifying function is performed by a transistor.

Tuned radio frequency receiver

A tuned radio frequency receiver is a type of radio receiver that is composed of one or more tuned radio frequency (RF) amplifier stages followed by a detector (demodulator) circuit to extract the audio signal and usually an audio frequency amplifier. This type of receiver was popular in the 1920s. Early examples could be tedious to operate because when tuning in a station each stage had to be individually adjusted to the station's frequency, but later models had ganged tuning, the tuning mechanisms of all stages being linked together, and operated by just one control knob. By the mid 1930s, it was replaced by the superheterodyne receiver patented by Edwin Armstrong.

Radio receiver Radio device for receiving radio waves and converting them to a useful signal

In radio communications, a radio receiver, also known as a receiver, a wireless or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.

Armstrong oscillator

The Armstrong oscillator is an electronic oscillator circuit which uses an inductor and capacitor to generate an oscillation. It is the earliest oscillator circuit, invented by US engineer Edwin Armstrong in 1912 and independently by Austrian engineer Alexander Meissner in 1913, and was used in the first vacuum tube radio transmitters. It is sometimes called a tickler oscillator because its distinguishing feature is that the feedback signal needed to produce oscillations is magnetically coupled into the tank inductor in the input circuit by a "tickler coil" (L2, right) in the output circuit. Assuming the coupling is weak, but sufficient to sustain oscillation, the oscillation frequency f is determined primarily by the tank circuit (L1 and C in the figure on the right) and is approximately given by

Push–pull output

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.

All American Five

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.

Electronic component

An electronic component is any basic discrete device or physical entity in 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.

A radio transmitter is an electronic device which, when connected to an antenna, produces an electromagnetic signal such as in radio and television broadcasting, two way communications or radar. Heating devices, such as a microwave oven, although of similar design, are not usually called transmitters, in that they use the electromagnetic energy locally rather than transmitting it to another location.

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.

Detector (radio)

In radio, a detector is a device or circuit that extracts information from a modulated radio frequency current or voltage. The term dates from the first three decades of radio (1888-1918). Unlike modern radio stations which transmit sound on an uninterrupted carrier wave, early radio stations transmitted information by radiotelegraphy. The transmitter was switched on and off to produce long or short periods of radio waves, spelling out text messages in Morse code. Therefore, early radio receivers had only to distinguish between the presence or absence of a radio signal. The device that performed this function in the receiver circuit was called a detector. A variety of different detector devices, such as the coherer, electrolytic detector, magnetic detector and the crystal detector, were used during the wireless telegraphy era until superseded by vacuum tube technology.

Reflex receiver

A reflex radio receiver, occasionally called a reflectional receiver, is a radio receiver design in which the same amplifier is used to amplify the high-frequency radio signal (RF) and low-frequency audio (sound) signal (AF). It was first invented in 1914 by German scientists Wilhelm Schloemilch and Otto von Bronk, and rediscovered and extended to multiple tubes in 1917 by Marius Latour and William H. Priess. The radio signal from the antenna and tuned circuit passes through an amplifier, is demodulated in a detector which extracts the audio signal from the radio carrier, and the resulting audio signal passes again through the same amplifier for audio amplification before being applied to the earphone or loudspeaker. The reason for using the amplifier for "double duty" was to reduce the number of active devices, vacuum tubes or transistors, required in the circuit, to reduce the cost. The economical reflex circuit was used in inexpensive vacuum tube radios in the 1920s, and was revived again in simple portable tube radios in the 1930s.

Antique radio Vintage telecommunication audio receiver

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

Transformer types Types of electrical transformer

A variety of types of electrical transformer are made for different purposes. Despite their design differences, the various types employ the same basic principle as discovered in 1831 by Michael Faraday, and share several key functional parts.

A transistor is a semiconductor device with at least three terminals for connection to an electric circuit. In the common case, the third terminal controls the flow of current between the other two terminals. This can be used for amplification, as in the case of a radio receiver, or for rapid switching, as in the case of digital circuits. The transistor replaced the vacuum-tube triode, also called a (thermionic) valve, which was larger and used significantly more power to operate. The introduction of the transistor is often considered one of the most important inventions in history.

AC/DC receiver design electrical equipment that operates on either alternating current (AC) or direct current (DC)

An AC/DC receiver design is a style of power supply of vacuum tube radio or television receivers that eliminated the bulky and expensive mains transformer. A side-effect of the design was that the receiver could in principle operate from a DC supply as well as an AC supply. Consequently, they were known as "AC/DC receivers".

The Pioneer SX-1980 was a radio receiver that Pioneer Corporation introduced in 1978, to be matched with the HPM series of speakers. It is rated at a staggering 270 watts per channel into 8 ohms. However, in the September 1978 issue of Audio Magazine, Leonard Feldman did a spec test on the SX-1980 and concluded that the rating of 270 watts per channel was too conservative. He stated in his report:

Though the new [IHF mandated] "Dynamic Headroom" measurement is specified in dB, it should be mentioned that based upon the short-term signal used to measure the 2.3 dB headroom of this amplifier, it was producing nearly 460 watts of short-term power under these test conditions!

References

  1. Lane, David; Lane, Robert (1994). Transistor Radios: A Collector's Encyclopedia and Price Guide . Wallace-Homestead Book Company. ISBN   0-87069-712-9. page 3
  2. 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. Retrieved 2010-04-20.
  3. Pies, Don (1998). "Regency TR-1 Transistor Radio History" . Retrieved 2019-02-19. and 140,000 TR-1's poured off the production line
  4. 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
  5. 1 2 Schiffer, M. B. The portable radio in American life. — University of Arizona Press, 1991. — P. 170–178. — 259 p. — ISBN   9780816512843
  6. Handy, Erbe, Blackham, Antonier (1993). Made In Japan : Transistor Radios of the 1950s and 1960s. Chronicle Books. ISBN   0-8118-0271-X.CS1 maint: multiple names: authors list (link) pages 15–17
  7. 1 2 Reyer, Steve (Dr.) "Regency TR-1 Transistor Radio Facts and Figures". Retrieved December 2, 2012
  8. 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
  9. Pies, Don (1998). "Regency TR-1 Transistor Radio History" . Retrieved 2019-02-19. Regency's master engineer, Dick Koch
  10. Regency schematic
  11. Lee, T. C. The Design of CMOS Radio-Frequency Integrated Circuits. — Cambridge University Press, 2004. — P. 271–272. — 797 p. — ISBN   9780521835398
  12. "Eveready 412 Carbon Zinc 22.5V Battery NEDA 215, 15F20, BLR122". Batteriesinaflash.com.