Analog device

Analog devicesare a combination of both analogmachineand analogmediathat can togethermeasure,record,reproduce, receive orbroadcastcontinuousinformation,for example, the almost infinite number of grades oftransparency,voltage,resistance,rotation,orpressure.In theory, the continuous information in ananalog signalhas an infinite number of possible values with the only limitation on resolution being theaccuracyof the analog device.

Analog mediaare materials with analog properties, such asphotographic film,which are used in analog devices, such ascameras.

Example devices

Non-electrical

There are notable non-electrical analog devices, such as someclocks(sundials, water clocks), theastrolabe,slide rules,the governor of a steam engine, theplanimeter(a simple device that measures the surface area of a closed shape), Kelvin's mechanicaltide predictor,acoustic rangefinders, servomechanisms (e.g. thethermostat), a simple mercurythermometer,aweighing scale,and thespeedometer.

Electrical

Thetelautographis an analogue precursor to the modernfax machine.It transmits electrical impulses recorded by potentiometers to stepping motors attached to a pen, thus being able to reproduce a drawing or signature made by the sender at the receiver's station. It was the first such device to transmit drawings to a stationary sheet of paper; previous inventions in Europe used rotating drums to make such transmissions.

Ananalog synthesizeris a synthesizer that uses analog circuits andanalog computertechniques to generate sound electronically.

Theanalog televisionencodes television and transports the picture and sound information as an analog signal, that is, by varying the amplitude and/or frequencies of the broadcast signal. All systems preceding digital television, such as NTSC, PAL, and SECAM are analog television systems.

Ananalog computeris a form of computer that uses electrical, mechanical, or hydraulic phenomena to model the problem being solved. More generally an analog computer uses one kind of physical quantity to represent the behavior of another physical system, or mathematical function. Modeling a real physical system in a computer is called simulation.

Example processes

Media

The chemical reactions inphotographic filmandfilm stockinvolve analog processes, withcameraas machinery.

Interfacing the digital and analog worlds

In electronics, adigital-to-analog converteris a circuit for converting adigital signal(usually binary) to an analog signal (current, voltage or electric charge). Digital-to-analog converters are interfaces between the digital world and analog worlds. Ananalog-to-digital converteris an electronic circuit that converts continuous signals to discrete digital numbers.