DIY Touch Sensor Light

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Project 2: DIY Touch Sensor Light

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.

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

Circuit Diagram:

(You can visualize this using Fritzing or Tinkercad.)

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.

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.

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.

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