Electronic Appliances Switch Left open Indicator

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Electronic devices, such as computers, printers, air conditioners, televisions, etc., use electricity when in use but still use some electricity when not in use; most electronic devices have power-off switches but still use some power when in use. That saves tons of fuel. But most of the time the users fail to fully shut down these devices, the given project is constructed with that in mind, the circuit will indicate after every minute when an appliance’s mains switch is left open by producing a sound signal.

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Hardware Components

The following components are required to make Switch Left open Indicator Circuit

S.no	Component	Value	Qty
1.	Resistors	1K, 470K	3, 1
2.	Capacitors	220uF, 0.01uF	1, 1
3.	Potentiometer	1M	2
4.	IC	LM358	1, 1
5.	IC	LMC555 or 7555	1, 1
6.	Transistor	2N4401	1
7.	Buzzer	–	1
8.	Antenna	–	1
9.	Diodes	1N4148	2
10.	lithium coin cells	6V	2

LMC555 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LMC555

LM358 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM358

Switch Left open Indicator Circuit

Working Explanation

The supply can be two 3V lithium coin cells after the circuit has been built connecting the supply with the circuit. The current circuit consumption is only 650uA so the batteries last longer. Use a small antenna wire for better performance, and position it next to the 220V AC electrical appliance cable. The circuit is very sensitive and the sensitivity can be modified with the connection of a 1M variable resistor. The circuit timing can be modified with the 1 M variable resistor connected between pin 6 and pin 7 of the IC2.

The circuit’s best feature is that it will not need any physical connections to the wire of the appliance, it just positions the antenna near the wire and does the rest.