Power Supply and Battery Backup for Pyroelectric Fire Alarm System

Power Supply and Battery Backup for Pyroelectric Fire Alarm System

Power Supply and Battery Backup for Pyroelectric Fire Alarm System. Power supply comprises a 0-12V, 1A step-down transformer having a standard full-wave rectifier formed by D1 through D4 and filter capacitor C1. A battery backup is supplied when the mains supply is cut-off because of short-circuit and fire. A 12V, 4.5Ah rechargeable battery is utilized for backup to provide enough current for the solenoid pump. When mains electrical power is available, diode D5 forward biases. It provides power towards the circuit and also charges the battery via resistor R2, and it limits the charging current to 120 mA. When power fails, diode D5 reverse biases and diode D6 forward biases, providing immediate backup for the circuit. LED1 signifies the availability of mains electrical power.

This schematic diagram come from circuit: Pyroelectric Fire Alarm System.
Go to that page to read the explanation about above circuit design.

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.

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