Pictured – An early transistor pocket radio by Motorola. The first Motorola brand automobile radio was produced in 1930. Motorola began the commercial production of transistors at a new \$1.5 million facility in Phoenix in 1955. This advertisement is from the May 23, 1960 issue of Life magazine.

Radio – the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels through the air and the vacuum of space. Information is carried by systematically changing ( modulating) some property of the radiated waves, such as amplitude, frequency, phase, or pulse width.

• Transmitter
• Tuner
• Amplifier – a device for increasing the power and/or amplitude of a signal. It does this by taking power from a power supply and controlling the output to match the input signal shape but with a larger amplitude. In this sense, an amplifier may be considered as modulating the output of the power supply.
• Speaker
• Power supply

First Pocket Radio – materials engineers at Texas Instruments were able to produce transistors in quantity so that another team of electrical engineers at IDEA could design, develop, and manufacture that first pocket radio.

Radios – A radio does three basic things. First, it harvests radio waves. Those waves are part of the electromagnetic spectrum, which is all around us. Second, the radio changes the signal from a selected station into an electric current. The force of that current, or its voltage, varies based on the sound information coded in the electrical signal.
What’s the problem?

Transistor – on October 16, 1947, physicists John Bardeen, Walter Brattain and William Shockley, applied the mathematics and science of quantum physics to semiconductors to invent the world’s first transistor. They had created a device that could amplify a weak electronic signal 18 times over a wide range of frequencies. For their efforts they received the Nobel Prize in 1956.
That’s engineering

• wave – a disturbance that propagates through space and time, usually with transference of energy. While a mechanical wave exists in a medium (which on deformation is capable of producing elastic restoring forces), waves of electromagnetic radiation (and probably gravitational radiation) can travel through vacuum, that is, without a medium.
• electromagnetic radiation – a self-propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation, and are in phase with each other.
• amplitude – A measure of the height of a recurring wave in some signal, water or beam of radiation. In sound, wave amplitude corresponds with intensity — loudness or softness.
• antenna (plural: antennae) – In biology: Either of a pair of long, thin sensory appendages on the heads of insects, crustaceans and some other arthropods. (in physics) Devices for picking up (receiving) electromagnetic energy.

Engineering ideas

• power, amplitude, signal, power supply, amplifier, transistor, frequency, modulate