Introduction: Three Touch Sensor Circuits + Touch Timer Circuit

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Touch Sensor is a circuit which turns ON when it detects the touch on the Touch Pins. It works on transient basis i.e. the load will be ON only for the time the touch is made on the pins.

Here, I will show you three different ways to make a touch sensor circuit :

1. Using Single Transistor

2. Using Two Transistors

3. Using 555 Timer IC

You can also make a Touch Timer Circuit (on adding a capacitor to 555 Timer IC circuit) which will allow the output to remain ON for some desired moment of time before turning it OFF.

Step 1: Components Required

These are the Components required for making the circuit:

1. Using Single Transistor

  • Touch Pins (2)
  • Transistors: BC 547
  • Resistors: 330 Ω
  • LED

2. Using Two Transistors

  • Touch Pins (2)
  • Transistors: BC 547 (2)
  • Resistors: 330 Ω
  • LED

3. Using 555 Timer IC

  • 555 Timer IC
  • Touch Pins (2)
  • Transistors: BC 547
  • Resistors: 330 Ω, 10K Ω
  • LED

Other Requirements :

  • Battery: 9V and battery clip
  • Breadboard
  • Breadboard Connectors

Step 2: Circuit Diagrams

These are the Circuit Diagrams for:

  • Single Transistor
  • Two Transistors
  • 555 Timer IC
  • Touch Timer Circuit

Step 3: Controlling Touch Timer Circuit

You can refer these values to control the time for which the output will remain ON in Touch Timer Circuit.

Step 4: Step-by-step Tutorial

This video shows step-by-step, how to build all these circuits.