Fire AlarmLCD-LED DisplaySecurity & Saftey

Basic alarm indicator

The most obvious alarm indication is a flashing light.This requires relatively complex electronics. however, to achieve correct flash-ing. Moreover, in certain circumstances, such as when the lamp is in bright light. -Lie indicator cannot be seen properly.

The present circuit is simplicity itself: it consists of only three components and provides not only a visual but also an audible indication. It is based on a special LED that contains the electronics to ensure that it lights periodically. When the LED is on, it draws a much larger current than in its quiescent state. This property is used to good effect. When the LED is out, hardly any current flow so that there is no voltage across the buzzer. When the LED is on, the relatively large current causes a drop across the buzzer, so that this sounds. The capacitor across the LED ensures sufficient butTering (decoupling) of the voltage across the diode. The circuit is actuated when a direct voltage of 7-9 V is applied to it.

The circuit draws a current of about 10 mA.

Basic alarm indicator Schematic diagram

A DC voltage is a constant voltage that drives the current in one direction. This means the current flows in one direction. However, it can vary over time. Rectifiers, solar panels, as well as batteries all, produce DC voltage from a chemical reaction. A voltmeter measures the DC voltage levels. Direct current (DC) is the flow of electric charge in only one direction. It is the steady state of a constant-voltage circuit. Most well-known applications, however, use a time-varying voltage source.

Direct current has many uses, from the charging of batteries to large power supplies for electronic systems, motors, and more. Very large quantities of electrical energy provided via direct current are used in the smelting of aluminum and other electrochemical processes When batteries discharge they emit a constant DC power in one direction, supplying electricity through the positive terminal to the negative. Most automotive components require this DC charge to work properly, but it is limited because batteries will eventually discharge completely, with no remaining power to give.27-Jun-2018

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