Understanding IC 555. Design note 3

We all used IC 555 in many applications. Why it is called as 555 Timer? There are three 5K resistors inside the IC that makes it as versatile IC for Timer applications. IC555 was introduced in 1971by the Signetics corporation as SE555 / NE555 and was called as IC555“IC Time Machine”. Later its CMOS version IC 7555 and Dual Timer IC 556 were introduced.
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Timely Beeper

You can fix this circuit in the switch board that provides power to the loads such as Water heater, Electric Iron etc to remind you that the load is switched on. LED blinks indicating the load on status and the buzzer beeps every 30 minutes. This helps to prevent the wastage of energy usually happens when we forget to switch off these devices. This can be also used to remind, if remote lights such a terrace light is switched on unnoticed.

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