DIY Touch Sensor Light

 

Project 2: DIY Touch Sensor Light

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Objective:

To create a simple touch-sensitive LED circuit that turns ON when you touch it and OFF when you release it, using a transistor as a switch.

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Components Required:

1. NPN Transistor – BC547
2. Resistors – 1MΩ & 330Ω
3. LED – Any color
4. Battery – 9V
5. Metal Touch Plate (or Bare Wire)
6. Breadboard & Connecting Wires

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Circuit Diagram:

(You can visualize this using Fritzing or Tinkercad.)

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Step-by-Step Instructions:

Step 1: Connect the Transistor

• Place the BC547 transistor on the breadboard.
• Connect the emitter (E) to the ground (-) of the battery.
• Connect the collector (C) to the negative leg of the LED.

Step 2: Connect the LED

• Connect the positive leg of the LED to the positive terminal of the battery via a 330Ω resistor.

Step 3: Add the Touch Sensor

• Take a metal plate or bare wire and connect it to the base (B) of the transistor via a 1MΩ resistor.
• Another wire from the metal plate should go to the positive terminal of the battery.

Step 4: Power the Circuit

• Connect a 9V battery or a 5V power source.

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How It Works:

1. When you touch the metal plate, a small electric charge from your body triggers the transistor, turning ON the LED.
2. When you release the plate, the transistor turns OFF, and the LED goes OFF.

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Customization Ideas:

💡 Use a Relay – Control high-power devices like bulbs or fans with touch.
💡 Use a Capacitor – Add a capacitor to hold the charge for a few seconds after touch.
💡 Use a MOSFET – Replace the transistor with a MOSFET for better sensitivity.