The radio, amplifier and speakers
Did you ever wonder how the Radio works? Let me explain it to you.
The components of the radio are:
- Circuit board
Radio relies on the radiation of energy from a transmitting antenna in the form of radio waves. Radio waves, traveling at the speed of light (186,000 miles per second), carry information. When these radio waves arrive at a receiving antenna, a small voltage is produced. After this voltage has been amplified, it is presented in understandable form through speakers.
The CHASSIS of a modern radio supports all the other components of the radio. The chassis supports the electronics of the TUNER and AMPLIFIER. The tuner is an electrical device that acts like a variable resistor. That is, it varies the frequency of the radio to receive the desired signal. Radio stations all broadcast on different frequencies, so a radio has to be able to distinguish one frequency from another. Radios have this ability with great precision.
The ANTENNA of a radio system is designed to pick up the signals broadcast from radio stations, and send those signals into the tuner circuitry. Honda cars after 1991 have antennas that automatic extend and retract. If the antenna gets bent, it will not extend or retract fully, causing the antenna motor to click several times.
The difference between AM and FM radio is that AM varies the strength of one frequency, while FM varies the frequency itself slightly to achieve what is stereo. All this is done by the use of electronic circuitry that consumes very little power.
The AMPLIFIER circuit inside the radio takes the incoming signal from the tuner, boosts it many times and then sends that signal to the speakers. The number of times the signal is boosted is dependent on the adjustment of the volume control knob.
The electrical signals broadcast from a radio station, received by the tuner, and amplified are then sent to the SPEAKERS. The speakers are constructed with a coil of wire that vibrates a paper cone at the same frequency as the tuner. Some speakers have additional amplifiers attached to them, which boost certain ranges of sounds produced by the speakers. This results in more volume of certain sounds. The tone, balance, fader controls are functions of the amplifier circuitry.
A stereo system may contain other items that manipulate and enhance the sound, such as graphic equalizers, dynamic range expanders or sub-woofers for more powerful bass. Due to the small nature of the radio chassis, other functions are sometimes added. Radios can now include tape players or compact disk players. These items are discussed in following chapters.
All radios installed in Honda and Acura automobiles after 1991 are equipped with anti-theft locking circuitry that renders the radio useless. If power is lost to the radio, a code is required to permit the radio to function again. Remember to keep the code card in a separate place from your car. Keeping it in the glove box gives a thief access to your radio code, defeating the anti-theft circuitry.
Most new cars are now equipped with a system called XM Radio. This system used signals broadcast to orbiting satellites and received by a small antenna on the roof of the car. The main benefit of this system is the ability to listen to the same program anywhere in the world, without interference and mostly commercial free. A small monthly subscription is required.
Some new cars even come with the ability to attach an iPod or MP3 player to play music through the radio.