The countdown timer

Are specialized timer clock that can be used to measure the duration of the process or incoming event. The timer can be a simple movement can be electromechanical, digital or software (implemented as part of a computer program).
Online timer

Mechanical kitchen timer (the "timer").Mechanical timers typically used classic clockwork spring and anchor, which regulates their speed.

Cheaper and less accurate are machines with an aerodynamic brake.

Electromechanical timerElectromechanical timers are of two types - with bimetal strip or with an electric motor.

Bimetallic stripThe bimetal strip is formed by joining two metal strips of different thermal expansion coefficient (typically steel and bronze), which is heated by passing an electric current. Bending the tape will contact separation, cooling and re-tape making contact again and the cycle repeats.

This type of timer is used eg for the blinkers in cars at the lights on the Christmas tree or the time limit congestion at the circuit breaker.Electric motorSimple electromechanical timer with an electric motor.AC electric motor spins the gear that moves the anchor as well as the classic movement. Are attached to the anchor electrical switch contacts and the current through the motor is precisely controlled.

Sometimes sprocket connected to a friction clutch that could be easily timer returned to the starting position.This type of timer is used for example in the washing machine, tumble dryer, dishwasher or in universal time switch.

The timer can take the form of a separate device (see illustration at right) plug adapter when the device is directly controlled socket for appliance or modular unit for cabinet mounting. Programming the timer stops is done and it is just gross. Typically after čtvrthodinách.
Digital timer provides more configurable switching intervals.

Digital timer achieves higher accuracy than mechanical or electromechanical, because it contains electronic clocks, quartz and special integrated circuit. Use of integrated circuits has caused such a drop in prices of digital technology, digital timers that are now cheaper than most mechanical timers.

Timers are manufactured as single-chip embedded systems like electronic watch.Many digital timers is currently implemented in single-chip computers with the software or the use of programmable logic circuits using Boolean algebra.In simpler (mainly amateur or handmade) circuits used integrated circuit NE555.

Digital timers use complicated devices that require higher precision or variability timers, for example, more expensive washing machine, dryer, dishwasher, or timers with more advanced options when setting switching intervals (repetition, switching only on selected days of the week, odd and even weeks, etc.) .


The digital timer is produced in the form of plug adapter (pictured) as well as a modular unit in the cabinet. They are equipped with real-time backup of the program. Subtle, but ubiquitous timers are stair machines that control lighting in common areas home.

Similarly, work time delay relays for fans to be off welfare facilities. These relays are installed in wiring boxes under the switch.The timer on the computerMost computers contain one to 16 hardware timers.

They are usually counters that the program is set to a value, which is then automatically reduced. When it reaches zero, the interrupt caused by the CPU is notified.

The timer is used to control the software events, such as time-out while waiting for an answer on another computer (English timeout), management scheduler in the operating system, etc.