المذياع الترانزستورى هوجهاز مستقبل إذاعى صغير مبنى على الترانزستور تاريخيا, مصطلح "الراديوالترانزستور" يشير إلى الراديوهووحيد القناة الإذاعية وعادةيستقبل فقط 540-1600 كيلوسيكل موجات بث إذاعى أى إم .

التاريخ

مختبرات بيل أظهرت الترانزستور الاول في 23 ديسمبر ، 1947. بعد الحصول على حماية براءة الاختراع ، والشركة عقدت تمؤتمرا صحفيا يوم 30 يونيوعام 1948 ، الذى فيه تم عرض النموذج الأولي الذي تجلى للراديوالترانزستور. هناك الكثير من المطالبين الى لقب اول شركة لانتاج اجهزة الراديوالترانزستور العملية ، وغالبا ما تنسب إلى سوني بدون تدقيق لصحة الأمر (أصلا طوكيوتسوشين كوجيو). تكساس أنسترومنتس قد عرضت أجهزة من الإصطلاح أجهزة راديو"كلها ترانزستورية" تعمل بتعديل السعة AM (amplitude modulation) وذلك في وقت مبكر من 1952, لكن أداءها كان أدنى بكثير من تلك النماذج التى تعمل بالأنابيب المفرغة. جهاز يعمل " الكل ترازستورى" جهاز الراديوالترانزستور تجلى في آب / أغسطس 1953 في دوسلدورف معرض الراديو من جانب الشركة الألمانية Intermetall. بنيت من أربعة من الترانزستورات Intermetall من خلق يدوي , استنادا إلى اختراع عام 1948 هربرت Mataré وهاينريش Welker. ومع ذلك ، كما هوالحال مع الوحدات التى أنتجتها تكساس أنسترومنتس في وقت مبكر (وغيرها)فإن نماذج فقط تم بناؤها على الإطلاق، ولكن لم تكن قط موضع الإنتاج التجاري.

تكساس أنسترومنتس كانت وراء الراديوالترانزستور ريجنسي. في أيار / مايو1954 ، وأنها قد وضعت بناء النموذج الأولى، وكانت تبحث عن مصانع إنتاج الأجهزة لتطوير وترويج واستخدام الراديوالترانزستور. لكن لا أحد من صناع الاذاعة الرئيسيون كانوا مهتمين بالأمر.

إن المذياع طرازريجينسى تى آر-1 , أطلق في أكتوبر 18, 1954 بواسطة قسم ريجينسى الهيئة الهندسية للتطوير الصناعى of I.D.E.A (Industrial Development Engineering Associates التابعة لإندياتابوليس,إنديانا) وعرض من أجل البيع في نوفمبر 1954 وكان بذلك أول حهاز مذياع ترانزستورى ينتج بأعداد كبيرة. وحصل على براءة اختراع من قبل ريتشارد كوتش C., US patent 2892931, موظف في الشركة. يكلف 49.95 دولار (حوالي 364 دولارا في عام 2006 دولار) وباع ما يقرب من 150،000 وحدة. رايثيون وذروة الالكترونيات أجهزة الراديوالترانزستور وسرعان ما تبعه ، وكان ثمنها أعلى من ذلك. حتى أول الواردات اليابانية (في 1957) وبثمن 30 دولارا وأعلاه. أجهزة الراديوالترانزستور لم تحقق شعبية كبيرة , حتى بداية الستينات عندما إنخفضت أسعار بعض النماذج تقلصت دون 20 دولارا (140 دولارا في عام 2009 دولارات) ، ثم أقل منعشرة دولارا كما أغرقت الأسواق وأصبحت مع أجهزة الراديومن هونج كونج من منتصف إلى أواخر 1960.

RCA had demonstrated a prototype transistor radio as early as 1952 and it is likely that they and the other radio makers were planning transistor radios of their own. But Texas Instruments and Regency were the first to offer a production model. Sony, at the time still a small company named Tokyo Tsushin Kogyo, Ltd., (aka "Totsuko"), followed soon after introducing their own five-transistor radio, the TR-55, in August 1955, under the new brand name Sony. With its release, Sony also became the first company to manufacture a radio from the transistors on up, and to utilize all miniature components.

Sony's first official import to the U.S.A. was the "pocketable" TR-63 released in March 1957, a model which proved highly successful in that market. (The term "pocketable" was a matter of some interpretation, as Sony allegedly had special shirts made with oversized pockets for their salesmen). In January 1958, the company changed its name to Sony, adopting the name that had previously been the reserve of its radio brand. The Sony TR-610 was released some months later, marking another resounding success and taking its place as the first transistor radio to sell more than a half-million units.

The use of transistors instead of vacuum tubes as the amplifier elements meant that the device was much smaller and required far less power to operate than a tube radio. It also allowed 'instant on', since there were no filaments to heat up. The typical portable tube radio of the fifties was about the size and weight of a lunchbox, and contained several heavy (and non-rechargeable) batteries: one or more so-called "A" batteries to heat the tube filaments and a large 45- to 90-volt "B" battery to power the signal circuits. By comparison, the "transistor" could fit in a pocket and weighed half a pound or less and was powered by standard flashlight batteries or a single compact 9-volt battery. (The now-familiar 9-volt battery was introduced for powering transistor radios.)

Listeners sometimes held an entire transistor radio directly against the side of the head, with the speaker against the ear, to minimize the "tinny" sound caused by the high resonant frequency of its small speaker enclosure. Most radios included earphone jacks and came with single earphones that provided only mediocre-quality sound reproduction due to the bandwidth limitation of AM (up to 4500Hz). To consumers familiar with the earphone-listening experience of the transistor radio, the first Sony Walkman cassette player, with a pair of high-fidelity stereo earphones, would provide a greatly contrasting display of audio fidelity.

The transistor radio remains the single most popular communications device in existence. Some estimates suggest that there are at least seven billion of them in existence, almost all tunable to the common AM band, and an increasingly high percentage of those also tunable to the FM band. Some receive shortwave broadcasts as well. Most operate on battery power. They have become small and cheap due to improved electronics which has the ability to pack millions of transistors on one integrated circuit or chip. The prefix "transistor" means a pocket radio; it can be used to refer to any small radio, but the term itself is now obsolete, since virtually all commercial broadcast receivers, pocket-sized or not, are now transistor-based.

Rise of digital audio player

Use of air signal only radios (AM/FM) have declined in popularity with the rise of portable digital audio players, which allow people to carry and listen to the music of their choosing and may also include a digital radio tuner. This is a popular choice with listeners who are dissatisfied with terrestrial music radio because of a limited selection of music or other criticisms. However, transistor radios are still popular for news, weather, live sporting events and emergency alert applications.

انظر أيضاً

• Broadcasting

الهامش

Further reading

• Michael F. Wolff: "The secret six-month project. Why Texas Instruments decided to put the first transistor radio on the market by Christmas 1954 and how it was accomplished." IEEE Spectrum, December 1985, pages 64-69
• Transistor Radios: 1954-1968 (Schiffer Book for Collectors) by Norman R. Smith
• Made in Japan: Transistor Radios of the 1950s and 1960s by Handy, Erbe, Blackham, Antonier (1993) (ISBN 0-8118-0271-X)
• Unique books on Transistor Radios by Eric Wrobbel
• The Portable Radio in American Life by University of Arizona Professor Michael Brian Schiffer, Ph.D. (The University of Arizona Press, 1991).
• Restoring Pocket Radios (DVD) by Ron Mansfield and Eric Wrobbel. (ChildhoodRadios.com, 2002).
• The Regency TR-1 story, based on an interview with Regency co-founder, John Pies (partner with Joe Weaver) www.regencytr1.com/Regency_Early_Years.html

وصلات خارجية

• http://www.jamesbutters.com/ Focusing on the history and design elements of early pocket transistor radios.
• http://www.pbs.org/transistor/materials/how-europe-missed-transistor.pdfPDF (946 KiB)
• TI Information Bulletin First Commercial Transistor Radio October 18, 1954
• Website about the first transistor radio by Dr. Steven Reyer, a Professor in the Electrical Engineering and Computer Science Department at the Milwaukee School of Engineering.
• M31 Galaxy of Transistor Radios Transistor radio site with photos and info on classic transistor radios from the US, Japan, and Europe.
• Radio Wallah Historical data accompanied by hundreds of images covering early transistor radios.
• Sarah's Transistor Radios Extensive website displaying over 1500 transistor radios and other information.
• : website with many historical references on the web and in published literature
• . In depth coverage of the Regency radio.
• Radio Expo is the source for the latest historical information about the Regency TR-1 & Regency Electronics
• Geocities Transistor radio directory