Editing Instrumentation (section)

===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.