Editing Instrumentation (section)

== Application ==
In some cases, the sensor is a very minor element of the mechanism. Digital cameras and wristwatches might technically meet the loose definition of instrumentation because they record and/or display sensed information. Under most circumstances neither would be called instrumentation, but when used to measure the elapsed time of a race and to document the winner at the finish line, both would be called instrumentation.

===Household===
A very simple example of an instrumentation system is a mechanical [[thermostat]], used to control a household furnace and thus to control room temperature. A typical unit senses temperature with a [[bi-metallic strip]]. It displays temperature by a needle on the free end of the strip. It activates the furnace by a [[mercury switch]]. As the switch is rotated by the strip, the mercury makes physical (and thus electrical) contact between electrodes.

Another example of an instrumentation system is a [[Burglar alarm|home security system]]. Such a system consists of 
sensors (motion detection, switches to detect door openings), simple algorithms to detect intrusion, local control (arm/disarm) and remote monitoring of the system so that the police can be summoned. Communication is an inherent part of the design.

Kitchen appliances use sensors for control.
*A refrigerator maintains a constant temperature by actuating the cooling system when the temperature becomes too high.
*An automatic ice machine makes ice until a [[Miniature snap-action switch|limit switch]] is thrown.
*Pop-up bread [[toaster]]s allow the time to be set.
*Non-electronic gas ovens will regulate the temperature with a [[thermostat]] controlling the flow of gas to the [[gas burner]].  These may feature a sensor bulb sited within the main chamber of the oven.  In addition, there may be a safety cut-off [[flame supervision device]]: after ignition, the burner's control knob must be held for a short time in order for a sensor to become hot, and permit the flow of gas to the burner.  If the safety sensor becomes cold, this may indicate the flame on the burner has become extinguished, and to prevent a continuous leak of gas the flow is stopped.
*Electric ovens use a temperature sensor and will turn on heating elements when the temperature is too low.  More advanced ovens will actuate fans in response to temperature sensors, to distribute heat or to cool.
*A common [[toilet]] refills the water tank until a float closes the valve. The float is acting as a water level sensor.

===Automotive===
Modern automobiles have complex instrumentation. In addition to displays of engine rotational speed and vehicle linear speed, there are also displays of battery voltage and current, fluid levels, fluid temperatures, distance traveled, and feedback of various controls (turn signals, parking brake, headlights, transmission position). Cautions may be displayed for special problems (fuel low, check engine, tire pressure low, door ajar, seat belt unfastened). Problems are recorded so they can be reported to  [[Vehicle bus|diagnostic equipment]]. Navigation systems can provide voice commands to reach a destination. Automotive instrumentation must be cheap and reliable over long periods in harsh environments. There may be independent [[airbag]] systems that contain sensors, logic and actuators. [[Anti-lock braking system|Anti-skid]] braking systems use sensors to control the brakes, while [[cruise control]] affects throttle position. A wide variety of services can be provided via communication links on the [[OnStar]] system. [[Autonomous car]]s (with exotic instrumentation) have been shown.

===Aircraft===
Early aircraft had a few sensors.<ref>[http://www.cap-ny153.org/aircraftinstrumentation.htm Aircraft Instrumentation – Leroy R. Grumman Cadet Squadron<!-- Bot generated title -->]</ref> "Steam gauges" converted air pressures into needle deflections that could be interpreted as altitude and airspeed. A magnetic compass provided a sense of direction. The displays to the pilot were as critical as the measurements.

A modern aircraft has a far more sophisticated suite of sensors and displays, which are embedded into [[avionics]] systems. The aircraft may contain [[inertial navigation system]]s, [[global positioning system]]s, [[weather radar]], autopilots, and aircraft stabilization systems. Redundant sensors are used for reliability. A subset of the information may be transferred to a [[Event data recorder|crash recorder]] to aid mishap investigations. Modern pilot displays now include computer displays including [[head-up display]]s.

[[Air traffic control radar beacon system|Air traffic control radar]] is a distributed instrumentation system. The ground part sends an electromagnetic pulse and receives an echo (at least). Aircraft carry transponders that transmit codes on reception of the pulse. The system displays an aircraft map location, an identifier and optionally altitude. The map location is based on sensed antenna direction and sensed time delay. The other information is embedded in the transponder transmission.

===Laboratory instrumentation===
Among the possible uses of the term is a collection of laboratory test equipment controlled by a computer through an IEEE-488 bus (also known as GPIB for General Purpose Instrument Bus or HPIB for Hewlitt Packard Instrument Bus). Laboratory equipment is available to measure many electrical and chemical quantities. Such a collection of equipment might be used to automate the testing of drinking water for pollutants.