This Adjustable Analog Timer circuit starts timing when switched on. A green LED lights to show that timing is in progress. When the time period is over the green LED turns off, a red LED turns on and a bleeper sounds. The time period is set by a variable resistor and it can be adjusted from 1 to 10 minutes (approximately). It could be used to set a time limit when playing games or as an egg-timer in the kitchen.
This schematic diagram come from circuit: Adjustable Analog Timer
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In the electrical sector, a schematic diagram is usually used to describe the design or model of equipment. Schematic diagrams are usually utilized for the maintenance and repair of electronic and electromechanical devices / units. Original schematics were made by hand, using standardized templates or pre-printed adhesive symbols, but nowadays Electrical CAD computer software is often used.
In electronic design automation, until the 1980s schematics were virtually the only formal representation for circuits. More lately, using the progress of computer system technology, other representations were introduced and specialized computer languages were developed, because with the explosive development of the complexity of electronic circuits, classic schematics are getting less practical. As an example, hardware description languages are indispensable for contemporary digital circuit design.