Hum Blocker Circuits. Simple Design 20

Hum is a nuisance in Amplifier circuits which is mainly due to improper filtering of AC fraction from the power supply and improper grounding. Hum will reduce the quality of sound from the speaker. You can easily eliminate the hum from the amplifier to get clear voice.
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DC Circuit Breaker. Simple Design 19

DC Circuit Breaker

This simple Circuit Breaker can be added to the Work Bench power supply, to break power to the load when the current flow through the load increases more than 470 mA due to short circuit or power surge. It immediately breaks the power to the load and the load again gets power only if the current flow returns to normal.
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Plant Wilt Sensor. Simple Design 18


This simple circuit tells you whether your Interior plant requires water or not. When the soil dry up, the Red LED lights to inform you that, the plant needs water. So this saves the life of your valuable interior plants.
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Kid’s Lamp. Simple Design 17

Child's Lamp 2

This simple White LED lamp is useful in Kid’s study room to get light when power fails. It avoids the Panic situation of sudden darkness and the Kid can go out easily. It turns on immediately when the room light turns off. It is too small, Matchbox size and is Battery operated. It remains off during daytime if there is day light in the room.
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Simple AC-DC Converter. Simple Design 16

AC-DC Converter
We need DC power supply for electronic circuits for that we use either a battery or a Step-down transformer. But cost effective power supply circuit can be designed to power low current devices like LED lights or similar simple circuits. Here is a Transformerless power supply using a Resistor and a few components to make a 12 volt power supply from 230V AC. It is too simple, light weight and can power simple circuits including Transistor and IC based circuits .The circuit is highly lethal and can give a fatal shock. Therefore, it should be constructed only if you are competent to handle high volt circuits.
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Fun with LED. Simple Design 15


LED is a wonderful semiconductor without which a circuit is generally incomplete. LEDs are used mainly as indicators to show whether the output of a particular section of the circuit is working or not. Let us see some simple circuits using LEDs that you can try.
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Lightning Counter. Simple Design.14

This simple circuit can detect electric discharge from Lightning and counts up to 9 and shows in a 7 Segment display. It is too simple to make using only one IC and a few components. Try it
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