Analogue, the word has been derived from the Greek word ‘analogos’, which means proportionate or ratio. Analogue computers make use of continuous signals to generate user understandable information, after the required processing. Most of the real-life signals are analogue or continuous in nature. For example, sound waves, light, voltage, current, etc are continuous in nature. In a nutshell, we are surrounded by continuous signals and analogue computers. But, most of us don’t pay much heed to them. Following are some types and examples of analogue computers:
Types of Analogue Computers
1. Slide Rules
It is one of the most basic analogue computing device designed in the early 17th century (around 1630s) by William Oughtred. Slide Rules was initially used for multiplication and division. A little later, it was found to be applicable in exponential, logarithmic, and trigonometric functions as well. Reportedly, the first crew that landed on the moon’s surface, led by Neil Armstrong had brought with them various electronic gadgets, including slide rules.
2. Differential Analysers
The differential analyser was invented by two engineers, Vannevar Bush and Harold Hazen, during the early 1930s. It was designed to solve complex differential equations. This technology makes use of mechanical arrangements to process the data and compute its solution. The differential analogue computers, however, have gone outdated today. But, they played a keen role in establishing a reliable foundation for the development of the technologies we utilize in today’s world.
3. Castle Clock
The castle clock is an 11 feet long antique clock, that employed some of the complex concepts of mechanical engineering for its operation. Other than displaying the time, it was also able to perform other functions such as showcasing solar and lunar orbits etc. Invented by Ismail al-Jazari, castle clock is one of the greatest inventions of all times. It was constructed during the first decade of the 13th century (around 1206). Hence, it is the oldest analogue computer known to us.
4. Electronic Analogue Computers
Earlier, electronic analogue computers were dependent on huge vacuum tubes for their operations. These tubes were bulky and required a lot of maintenance. However, modern electronic analogue computers use a network of electronic components, such as resistors, capacitors, inductors, transistors, etc. The electrical signal flowing through this network or circuit experiences variations in amplitude, frequency, phase, and other related properties. This change is used accordingly to generate the essential result. Various examples of electronic analogue computers include spectrometer, oscilloscope, etc.
5. Mechanical Analogue Computers
Mechanical Analog Computers, as the name suggests, make use of mechanical parts like gears, shafts, cams, etc to perform the computations such as multiplication, division, etc. These type of computers are rough and tough to use and have a number of applications in daily life. For example, mechanical clocks, mechanical calculators, mechanical counters, etc. Other mechanical computers may also use pneumatic and hydraulic theories. On dividing a number by zero, a mechanical calculator behaves in a chaotic manner.
Examples of Analogue Computers
An analogue thermometer makes use of a graduated scale and properties of mercury, to fulfil its operation. Mercury, which is liquid at room temperature, expands upon heating. Thereby, allowing the consumer to diagnose the feverish state of the body. Body temperature is an analogue signal. Therefore, a thermometer that measures body temperature is a perfect example of analogue computers.
The speedometer is a device that detects the current speed of a particular vehicle. The scale of the speedometer is properly graduated, usually in kilometres per hour. The Speed is pointed with the help of a needle that is allowed to deflect freely according to the analogue signal received by it. The speedometer cable is attached to the gear shaft on one end, and to a permanent magnet on the other end. This magnet is coupled to a metallic speed cup with no physical connection between them. The speed cup is connected to the indicator with the help of an inductor rod having a spring attached to it. The spinning outer shaft of the gearbox rotates the magnet. The magnetic field generated by the moving magnet attracts the metallic speed cup. This mechanical movement of the speed cup is used to deflect the needle. This deflection of the needle indicates the speed of the vehicle.
3. Analogue Clock
An analogue clock is quite frequently used gadget in our day to day life. Many of us are not aware that, an analogue clock is a form of analogue computer. It makes use of quartz crystal that is susceptible to the piezoelectric effect. The voltage provided by the battery, an analogue signal, allows the piezoelectric crystal to vibrate at a rate of exactly 32,768 vibrations per second. With help of these vibrations, a pulse is generated. This one pulse is the time equivalent of one second. So one second equals 32,768 vibrations of the piezoelectric crystal. It’s interesting, isn’t it?
The seismometer is a device used to note the information related to an earthquake. This device is kept in close contact with the earth’s surface. When the earthquake occurs, the earth shakes, and so does the seismometer. The waves produced during an earthquake are called seismic waves. Seismic waves are then recorded on the graph paper present in the setup, called a seismograph. The seismologists, then tell us about the intensity of the earthquake after proper study and analysis.
Voltage is an analogue signal because it varies constantly with respect to time. Therefore, analogue voltmeters can be regarded as analogue computers. A voltmeter is used to display the potential difference existing between two points of an electrical network. Analogue voltmeters mainly consist of a deflecting needle and a curved graduated scale on the display unit. The voltmeter is connected in parallel with the circuit in order to measure the subsequent voltage drop across the resistor.
6. Flight Simulators
During a flight, the pilot may experience a lot of extremities including bad weather, engine failure, runway tyre blow out, etc. It is extremely important for a pilot to experience all sorts of problems beforehand so that he doesn’t panic if and when the time comes. Since it would be inappropriate and impossible to create such scenarios in real life. Therefore, during the training of a pilot, a flight simulator is used to create an illusion of all such problems. The simulator creates an exact replica of the real cockpit with use of hydraulic pumps, image generators, sound systems, motion actuators, etc. All such computing elements deal in real-life or analogue signals, which allows us to put flight simulators under the category of analogue computers.
7. Tide Predictors
Tide predicter is an ideal example of a mechanical analogue computer. It makes use of mechanical machinery to note the height of tides at regular intervals. Tides are caused due to the gravitational pull experienced by the water present on the earth’s surface from the earth, the sun and the moon. The location and motion of these three celestial bodies are very well known, which is why it is easy to predict tides in a precise manner. Whenever an irregularly high tide is observed, the machine sends an alert. Water waves are analogue in nature, hence tide predictors are analogue devices.