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Circuit symbol of a heptode. The development of the pentagrid or heptode (seven-electrode) valve was a novel development in the mixer story. The idea was to produce a single valve that not only mixed the oscillator signal and the received signal and produced its own oscillator signal at the same time but, importantly, did the mixing and the oscillating in different parts of the same valve.
The term radio receiver is understood in this article to mean any device which is intended to receive a radio signal in order to generate useful information from the signal, most notably a recreation of the so-called baseband signal (such as audio) which modulated the radio signal at the time of transmission in a communications or broadcast system.
VEF Spīdola (1960) Restyled VEF Spīdola-10 (1963) VEF Transistor-10 (1965), export issue of VEF Spīdola-10, with additional short wave band. Also known in UK as Convair-10 VEF Spidola ( Latvian : VEF Spīdola , Russian : ВЭФ Спидола ) was the first mass-produced transistor radio with short wave band in the Soviet Union (tube short ...
Schematic representation of the elementary component of a transmission line The transmission line model is an example of the distributed-element model . It represents the transmission line as an infinite series of two-port elementary components, each representing an infinitesimally short segment of the transmission line:
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.
An early 2000s transistor radio (Sony Walkman SRF-S84 transistor radio, released 2001, shown without earphones) Rock 'n roll music became popular at the same time as transistor radios. Parents found that purchasing a small transistor radio was a way for children to listen to their music without using the family tube radio.
The schematic diagram shows a typical TRF receiver. This particular example uses six triodes. It has two radio frequency amplifier stages, one grid-leak detector/amplifier and three class ‘A’ audio amplifier stages. There are 3 tuned circuits T1-C1, T2-C2, and T3-C3.
The transistor both amplifies and rectifies the amplitude modulated (AM) radio signal. Since the base-emitter junction acts as a diode it conducts only on the positive half-cycles of the carrier wave, blocking the negative half cycles, rectifying the carrier to extract the audio modulation signal from the radio wave. The collector current is an ...